Unit 3 - Pattern Analysis PDF

Unit 3 Pattern Analysis Casts, Impressions, and Tool Marks  Introduction People, vehicles, and objects leave evidence of their presence at an accident or crime scene. Patent impressions are two-d...

Unit 3 Pattern Analysis Casts, Impressions, and Tool Marks  Introduction People, vehicles, and objects leave evidence of their presence at an accident or crime scene. Patent impressions are two-dimensional Latent impressions are hidden to the eye Plastic impressions are three-dimensional 3  Shoe Impressions Shoeprint size indicates the foot size The depth of a foot or shoe impression indicates a person’s weight The type of shoe can tell something of the person’s job or personality Databases contain the names of specific manufactures and tread designs 4  Shoe Wear Patterns Factors that personalize a person’s footwear: Body weight The way a person walks – Weight distribution – Direction of toes (straight, pointing out or in) The surface on which the person walks Unique holes, cuts, and debris embedded in the tread 5  Collection of Shoe Impression Evidence Why would the following steps be important? 1. Take photos as soon as possible 2. Take multiple photos of the impression from at least two different orientations 3. Place an identifying label and a ruler in position with the impression for the photo 4. Use oblique lighting when possible 6  Lifting Latent Impressions Different methods to make latent prints visible: Luminol makes bloody footprints visible for photography Dusting the latent print reveals an impression for lifting or photography Electrostatic lifting and gel lifting (image below) techniques can capture hidden impressions 7  Electrostatic Dusting and Lifting Electrostatic dusting reveals dust left with each step and creates an impression Electrostatic charges can lift impressions from paper carpeting wood surfaces linoleum asphalt concrete Gel lifters also recover latent impressions 8 Forensic Science: Fundamentals & Investigations, Chapter 15 ESDA  Shoe Impressions New Technique IN is the first state to have approved a new method for lifting shoe impressions from snow/dirt They can now use Great Stuff Insulating Foam  Another method… We can also use Vaseline and magnetic powder from fingerprinting Thin layer of Vaseline on the shoe; step onto paper, then use the magnetic powder Comparing Shoe Size and Height 12  Tire Treads and Impressions Tire treads—ridges and grooves channel water away and provide traction Patent tread patterns—impressions made after tire runs through a fluid material Latent tread patterns—impressions from tire oils used to keep tires soft and pliable Plastic tread patterns—three dimensional impressions left in soft surfaces 13 Anatomy of a Tire 14  Recording Tread Impressions Count ridges and grooves across the tire width Note unique characteristics—wear or pebbles embedded in the grooves Create a print of the suspect’s tire impressions through one revolution Compare impressions from the crime scene and suspect’s tire Identifying tread patterns may not be enough to link a suspect with a crime scene 15  Identifying a Vehicle Track widths— From center of tire to center of tire Wheelbase length— From center of front axle to center of rear axle 16  Identifying a Vehicle Turning diameter Databases can be checked to find the vehicle with these specifications 17  Dental Impressions Occasionally a perpetrator will leave behind a bite mark—considered individual evidence Note differences in the size of teeth and jaws, position, fillings, crowns, caps, breakage, and crowding 18 Development of Teeth 19  Dental Patterns in Forensics The investigation consists of recognizing, docu-menting, collecting, and analyzing evidence What are the two basic ways dental patterns can be used in forensic investigations? There are 76 points of comparison when comparing a suspect’s dental patterns with bite marks left at a crime scene What is the common method used to reveal whether there is a match? 20................. Summary Impression evidence—whether patent, latent, or plastic— will be considered class evidence unless it has individualizing features. Debris patterns and tire marks can be clues to speed, direction, and vehicle identification. Differences in dental patterns can connect a person to a crime scene. Documentation (including early photos) is extremely important in an investigation. 21  Introduction Tool mark—any impression, abrasion, or cut made when contact occurs between a tool and an object – An example of physical evidence – Even mass-produced tools have minor differences – The impressions can link the tool to a crime scene and potentially to the owner 22  Tools and Crime Scenes Tools: – increase our ability to handle manual tasks, but – can also be used in crimes How can a tool used in a crime lead investigators to the criminal? Why is ownership of a tool used in a crime circumstantial evidence? 23  Tool Mark Impressions Indentation Marks Result when a tool is pressed against a softer surface Tools usually leave distinctive marks The hardness of a tool influences the resulting marks left in the softer object May indicate the size of the tool used in a crime 24  Tool Mark Impressions Abrasion Marks An object’s surface can be ground or worn away by a tool The harder object causes abrasions on the softer surface Indentation and abrasion marks sometimes occur at the same time 25  Tool Mark Impressions Cutting Marks Edged instruments can penetrate a softer object and separate it into parts Cut marks are produced along the edge as a surface is cut 26  Tool Mark Impressions Examples of Cut Marks on Bones 27  Blade Examples Stryker saw band saw hack saw Chain saw table saw  Tool Mark Examination Some experts specialize in tool mark investigations Evidence can include: – tool marks at the scene – the tool if left behind 29  Documenting the Evidence Collect tool mark evidence when possible Photograph the evidence with a measuring device to show scale Measure the size of the impression 30  Documenting the Evidence Castings preserve tool mark impressions – silicone or rubber-based casting materials Cast impressions retain the unique indentation marks made by a specific tool 31  Documenting the Evidence Dust for fingerprints before applying casting material – Use magnetic dusting powder and silicone material The size of the impression should be measured and recorded. 32  Collecting and Preserving a Sample Correctly label evidence Wrap small objects with clean paper and place them in small containers or plastic bags Pack large objects in cartons or boxes Record—who, where, when, and why Maintain the chain of custody 33  Analyzing Tool Mark Evidence Laboratory tool mark analysis identifies: – major characteristics defining the type of tool used in a crime – unique characteristics that might distinguish between the same kinds of tools Forensic comparison microscopes examine tool mark characteristics that match a suspect tool 34  New Technology in Tool Mark Identification Courts now require more than visual pattern comparisons Tool mark databases (with images acquired by forensic comparison microscopes) Algorithms to statistically analyze tool mark patterns Scanning tools measure the depth or height of tool marks 35  Tool Mark Evidence in the Courtroom The tool mark witness prepares a written report to present to a jury. When available, provide: – Original evidence – Castings – Magnified images of tool mark comparisons Such evidence may link a series of crimes 36................. Summary Tools have major and minor surface differences Tool marks are indentations, abrasions, or cut marks Impressions made by tools could link them to a crime scene and ultimately to the owner Tool mark evidence should be photographed, documented, and collected or cast 37 Fingerprints  Historical Development 1. 3rd century B.C. in China—oldest known documents 2. Ancient Babylon (1792-1750 B.C.)—fingerprints pressed into clay tablets marked contracts 3. 1684—Dr. Nehemiah’s paper describes the patterns on human hands, including the presence of ridges 4. 1788—Johann Mayer noted that the arrangement of skin ridges is never duplicated in two persons 39  Historical Development 5. 1823—Jan Evangelist Purkyn describes nine fingerprint patterns 6. 1856—Sir William Herschel (right) began the collection of fingerprints and noted they were not altered by age 7. 1883—Alphonse Bertillon created a way to identify criminals that were repeat offenders 40  Historical Development 8. 1888—Sir Francis Galton (r) and Sir Edmund Richard Henry developed the fingerprint classification system still used in the US 9. 1891—Iván (Juan) Vucetich collected all ten fingerprint impressions and noted measurements 10. 1896—Sir Henry, with two colleagues, created a system that divided fingerprints into groups. All ten fingerprints are imprinted on a card (called a ten card) along with other notations 41  History of Fingerprinting Alphonse Bertillon’s anthropometry system: – A system of personal identification developed in 1883 – Measurements of the bony parts of the body – Morphological description of the appearance and shape of the body – Description of marks observed on the surface of the body Bertillon’s system was used until 1903, when it was proven to be unreliable  History of Fingerprinting Authorities realized that two people could share identical measurements and facial features, but had unique fingerprints. – Will West v William West case – Both appeared to be identical twins, however, their fingerprints were unique to each other The first practical use of fingerprints (1858) occurred with illiterate Indians to prevent forgery on legal documents.  History of Fingerprinting Sir Francis Galton developed the first classification system for fingerprints. – 1901: first U.S. use of Galton system (by New York City Civil Service Commission) – 1903: Galton system implemented at New York State Prison System and at Leavenworth Penitentiary – After 1903: Galton system used by police departments in major cities – 1924: records of FBI and Leavenworth Penitentiary merged and moved to Washington, D.C.  History of Fingerprinting Sir Edward Henry: developed a more workable classification option for fingerprints in the late 1890’s – It was later implemented when he became Assistant Commissioner of Scotland Yard – Henry’s system adopted by most English speaking countries Juan Vucetich: an Argentinean police official developed a system used by most Spanish speaking countries  What Are Fingerprints? All fingers, toes, feet, and palms are covered in small ridges Ridges help us grip objects Ridges are arranged in connected units called dermal, or friction, ridges Fingers accumulate natural secretions and dirt Fingers leave create prints on objects we touch 46  Characteristics of Fingerprints Fingerprints are unique to a particular individual. No two fingerprints have the exact same set of characteristics. Fingerprints do not change over a person’s lifetime or with superficial injury. Fingerprint patterns can be classified. Fingerprints do not provide proof of genetic history or racial background. It is not possible to change one’s fingerprints, although some have tried.  Formation of Fingerprints Skin consists of: – Inner layer—dermis – Outer layer—epidermis – Basal layer in between as a part of the epidermis Basal layer grows faster than the layers above and below it Basal layer collapses and folds to form intricate shapes Fingerprints begin forming near the 10 th week of pregnancy 4 total layers of skin (4th is the sub-cutaneous tissue) 48 Structure of Skin 49 Figure 6-2  Characteristics of Fingerprints Forensic examiners look for – Core (the center of a whorl or loop) – Deltas (triangular regions near a loop) Ridge count – Counting from the core to the edge of the delta – Distinguishes one fingerprint from another 51  Characteristics of Fingerprints There are 3 general fingerprint distinctions: ARCH WHORL LOOP About 5% About 30% About 65% of the population 52  Characteristics of Fingerprints Loops: friction ridges enter from one side of the print, curve around, and then exit the same side they entered – Ulnar loop (left hand): enters and exits from the left – Radial loop (right hand): enters and exits from the right  Characteristics of Fingerprints Whorls: inner area of the pattern consists of one or more ridges that make a complete circuit between two deltas – Plain whorl: examiner draws a line between two deltas and the line touches the ridge lines – Central pocket loop: ridge lines are not touched – Double-loop whorl: two separate and distinct loop formations – Accidental whorl: more than two deltas  Characteristics of Fingerprints Arches: no deltas and no significant core – Tented arch: ridge lines rise and fall rapidly Characteristics of Fingerprints 56 Characteristics of Fingerprints 57  Characteristics of Fingerprints Basic patterns can be further divided: – Arch patterns: 4% plain 1% tented – Whorl patterns: 2% central pocket 4% double loop 0.01% accidental Even twins have unique fingerprints 58  Fingerprint Identification Points A single fingerprint may contain as many as 100 or more minutiae that can be used for identification purposes. Debate continues over how many details must be the same to declare two fingerprints a match.  Methods for Developing Fingerprints Latent fingerprint: not readily visible to the naked eye Patent fingerprint: visible to the naked eye Plastic fingerprint: impression left on the surface of a soft material such as clay, tar, or wet paint  Methods for Developing Fingerprints Finding latent prints requires the use of differing techniques to help visualize the print. – Powders are used when the surface is smooth. – Chemicals are used for soft and porous surfaces.  Methods for Developing Fingerprints Recovery from hard surfaces – Black powder: applied to white or light-colored surfaces – Gray powder: applied to dark-colored surfaces, mirrors, and polished metal surfaces – Fluorescent powder: fluoresces when viewed under ultraviolet light – Carbon/charcoal and aluminum powders: applied with a fiberglass or camel’s hair brush – Magnetic-sensitive powders: spread with a Magna Brush  Methods for Developing Fingerprints Recovery from hard surfaces – After dusting, the print should be photographed and lifted from the surface. – A hinge lifter includes an adhesive sheet for lifting the fingerprint, plus a backing sheet to seal and protect the fingerprint.  Methods for Developing Fingerprints Small particle reagent (SPR) – Consists of finely ground particles suspended in a detergent solution – Used to recover fingerprints on oily or wax- covered surfaces  Methods for Developing Fingerprints Recovery from soft surfaces 1. Iodine fuming 2. Ninhydrin 3. Silver nitrate 4. Super Glue fuming  Fingerprint Forensic FAQs How are latent fingerprints collected? 66  Methods for Developing Fingerprints Iodine fuming – Object is placed in an enclosed chamber with iodine crystals – Temperature is increased until iodine sublimes – Iodine vapors react with body oils and make print visible – Print must be photographed immediately – Print can be sprayed with 1% solution of starch in water to turn the print blue and make it last longer  Methods for Developing Fingerprints Ninhydrin – 0.6% solution of ninhydrin powder is dissolved in acetone or ethyl alcohol and sprayed onto the surface – Prints appear in an hour or two – Reaction can be accelerated if the object is heated to 80–100 °C – Reaction of ninhydrin with amino acid from perspiration forms a purple-blue product called Ruhemann’s purple  Methods for Developing Fingerprints Silver nitrate – Used after trying iodine fuming and ninhydrin – 3% solution of silver nitrate is brushed onto suspected object – When object is exposed to ultraviolet light, the print turns reddish brown or black  Methods for Developing Fingerprints Super Glue fuming – Suspect material and super glue fumes react up to 6 hours in enclosed chamber – In automobiles, a wand can be used to direct fumes to the area of interest – Often then treated with RAY to help develop color  Preservation of Fingerprints Objects thought to hold latent prints should be carefully collected and submitted to the lab. The investigator may have to develop prints at the scene if removal of the object is not possible. Developed prints must be carefully photographed.  Preservation of Fingerprints Photography of fingerprints – Still photography exploits the selective absorption of light by different colors on the surface of the object. – A clearly visible fingerprint can be photographed with a white light source (e.g., a tungsten light bulb). – Use an excitation filter in front of a white light source for a colored print on a colored surface. – Use a filter that is opposite in color to the color of the fingerprint, but close in color to the background substrate.  Preservation of Fingerprints Digital imaging of fingerprints – Digital imaging’s higher resolution translates into more detail. – Most digital cameras use a charge-coupled device to produce high-quality images. – The fast Fourier transform (FFT) computer program can convert the digital image and eliminate background noise. – FFT is useful in developing a single print from a object containing multiple, overlapping prints.  Automated Fingerprint Identification System AFIS classifies fingerprints based on the distance between the core and delta, minutiae locations, and pattern type The FBI released the Integrated AFIS (IAFIS) in 1999 – Now called NGI – next generation identification Most modern AFIS systems compare fingerprint minutiae The systems concentrate on points where forensic ridge lines end or where one ridge splits into two (bifurcation) Indiana’s AFIS system now takes about 5 minutes  Automated Fingerprint Identification System Having the same number of minutiae is not enough to declare a match; individual minutiae must also be located at the same place on each print. The scanner system identifies matching minutiae patterns. The exact number of matches needed for positive identification depends on the country; there is no set number for the United States or United Kingdom. – Lorinda in our lab usually tries for 8 points  Levels on a print Level 1 = flow/pattern (arch, whorl, loop, etc.) Level 2 = minutiae (delta, bifurcation, etc.) Level 3 = texture/edgeoscopy – I will let Lorinda explain this level…  Fingerprints for Biometric Identification Biometrics entails the authentication of the identity of an individual using fingerprints, palm prints, retinal scans, or other biological signatures. The computer compares the applicant to a relatively small number of possibilities in its database of authorized users.  Fingerprints for Biometric Identification Finger scanning – Most departments currently use optical finger scanners for scanning fingerprints. – Scanners can be adjusted to alter the exposure, reposition fingers, and assure clarity of scans. – A computer algorithm identifies minutiae points on the scanned print and locates them relative to other points on the print.  Fingerprints for Biometric Identification Biometrics-related issues – If your fingerprints fall into the hands of a criminal, you could have serious problems for the rest of your life. – The Enhanced Border Security and Visa Entry Reform Act of 2002 mandated use of biometrics for issuance of a U.S. visa.  Fingerprint Forensic FAQs Can fingerprints be erased? Only temporarily; they will grow back if removed with chemicals Is fingerprint identification reliable? Yes, but analysts can make mistakes Can computers perform matches in seconds? No, but the FBI’s Integrated Automated Fingerprint Identification System (IAFIS or AFIS) can provide a match in 2 hours 80  The Future of Fingerprinting New scanning technologies – Yield detail in minute patterns – Reduce analytical mistakes – Analyze trace elements of objects on the skin Technologies that recognize patterns in – Retina – Face – Veins in your palm 81.............. Summary.... Fingerprints have long been used for identification, and in the mid-1800s were recognized as unique to each person. Three main groups include arches, whorls, and loops. Basic analysis includes looking for cores and deltas and making a ridge count. Any DNA matches from CODIS then go to fingerprints to rule out identical twins 82  Questioned Documents Handwriting analysis, forgeries, and a little TLC  Introduction Questioned document: – An object that contains typewritten or handwritten information, but whose authenticity has not yet been definitively proven – Authenticity must be demonstrated by a document examiner Forgery: – A person creates a document or alters an existing document in an attempt to deceive people  Handwriting The writing of an individual will vary over a natural range. Handwriting can be used as a means of identification if enough samples are available. Known writings (exemplars) should be as similar as possible to the questioned document. – The writing implement and paper used for an exemplar are important.  Handwriting Development of handwriting – Children’s writing is very similar. – Handwriting becomes more individualized as a person ages. – Handwriting in adulthood stays basically the same with only minor changes. – A decline in motor skills as one becomes elderly can alter handwriting. – The use of drugs and medication can affect a person’s handwriting  Handwriting Unlike fingerprint analysis, handwriting analysis can be subjective and must be carefully considered  Introduction to Handwriting Everyone’s handwriting shows natural variations. Here are 6 of the 12 major, specific traits. 88  Introduction to Handwriting The traits are functions of formatting or of letter or line form. Here are the other 6 of the 12 major, specific traits. 89  Handwriting Examination 1. Two writings came from one person if: – their similarities are unique and – no unexplainable difference(s) are found 2. Examine the questionable document for detectable traits and record them 3. Obtain a known sample of the suspect’s writing (an exemplar) 4. Compare and draw conclusions about the authorship of the questionable document 90  Technology Used in Handwriting Analysis Biometric Signature Pads – “Learns” to recognize how a person signs – Evaluates speed, pressure, and rhythm of the signature – Recognizes forgeries by the detection of even slight differences Computerized Analysis – Compares handwriting samples objectively – Compared with samples stored in databases 91  Handwriting Comparison of handwriting – Block capitals: uppercase unjoined letters – Cursive: lowercase letters joined together within a word – Script: lowercase unjoined letters The normal handwriting of most people is a combination of cursive and script writing. The document examiner compares all characters in a document to locate unique handwriting traits.  Handwriting Important handwriting features – Style of writing – Shape of letters – Slope or slant of writing – Spacing of letters – Spacing of words – Initial strokes – Terminal strokes – Connecting strokes Figure 7-2  Handwriting Comparison of handwriting – Examination is usually carried out using a low- power stereomicroscope or magnifying glass Reticle: eyepiece for a magnifying glass that contains a grid of fine lines to determine the position of letters being examined – Handwriting slope can vary from 50° forward to 10° backward from vertical – The direction of pen movement can indicate whether the writer is right- or left-handed  Handwriting Collection of handwriting exemplars – Need to assess when the comparison document was created relative to the questioned document – Two types of exemplars are possible: Unrequested specimen: author had no idea it would be used for a comparison Requested specimen: suspect is asked to produce a specimen  Handwriting Evidence in the Courtroom – Expert explains how comparisons were made – Cross-examination by defense attorney may follow Shortcomings in Analysis – Are the base documents real or fake? – Did mood, age, fatigue impact the handwriting? – Did experts miss details any details? 97  Handwriting Gilbert v. California – Law enforcement officers are allowed to obtain handwriting samples before suspects obtain legal counsel – Handwriting samples are identifying physical characteristics not protected by the Fifth Amendment United States v. Mara – Taking of a handwriting specimen does not constitute an unreasonable search of a person and is not a violation of the individual’s Fourth Amendment rights  Handwriting Steps to reduce specimen alteration – Furnish the suspect with pen and paper similar to those used to create the questioned document – Never show the suspect the questioned document – Do not provide help with spelling, punctuation, capitalization, or grammar – Dictate text that contains as many of the same words and phrases that appear in the questioned document as possible – Dictate the text three times  Signatures Signatures are intentionally highly stylized and are never identical on two different occasions. They are usually forged for financial gain.  Signatures Forgery methods – Freehand method: practice making a person’s signature until the forger can recreate it – Trace-over method: trace over the authentic signature so that an indentation is made on the document below – Light-box method: illuminate an authentic signature with a light box or window, trace it using a pencil, and ink over the trace later – Lifting: lift an authentic signature created with erasable ink using frosted Scotch tape  Signatures Handwriting comparison programs – Assess natural differences in handwriting to find all possible variations in questioned and exemplar documents – Create a statistical table citing the differences to provide an objective basis for the final conclusion as to the author of a document  Erasures, Obliterations, and Alterations Erasures – Parts of a document may be erased using rubber erasers, razor blades, sandpaper, etc. – Abrasion on the surface can be easily seen under a low-power microscope using a tungsten light bulb. Obliterations and other alterations – A forger may use chemical treatment to remove writing or black out an area to conceal the original writing.  Indented Writing Indented writing: the impression left by a pen on a second sheet of paper below the original writing Detection: relies on an electrostatic detection apparatus (ESDA) – ESDA can reveal indentations four or more pages below the original writing – Documents analyzed with ninhydrin for latent prints cannot be analyzed with ESDA Figure 7-11  Typed and Word-Processed Documents Typed documents – Typewriters wear in a random and irregular way that imparts individual characteristics to the machine. – Familiarity with the specific typefaces used by typewriter manufacturers helps identify the model and manufacturer of the typewriter used to produce a document. – Computer-based printers have almost completely replaced typewriters today.  Typed and Word-Processed Documents Word-processed documents – Computer printers may not establish enough individual characteristics to identify the specific printer that produced a document. – Letters from ink-jet printers are more blurred and not as sharp as letters from laser printers. – The examiner may be able to link a document to a suspected laser printer or show that two documents were printed on the same laser printer.  Typed and Word-Processed Documents Word-processed documents – A document’s class characteristics can identify the make and model of laser printer that produced it. – The examiner can identify the type of toner, chemical composition of toner, and type of fusing method used to produce the document. – Databases can help determine the manufacturer and model type that made the document.  Photocopied Documents Characteristic marks: marks on the paper copy that may permit identification of the manufacturer and model of the photocopier that produced the document – Imperfections on the drum forming the image may produce irregularly shaped characters. – Specks or marks on the copy might result from dirt or scratches on the glass window. – The toner used by each manufacturer have a slightly different chemical composition.  Forgery Forged documents include: – checks – employment records – legal agreements – licenses – wills Fraudulence—forgery for material gain 110  Forgery Check forgery can include: – ordering another’s checks from a deposit slip – altering a check – intercepting another’s check, altering, and cashing it – creating a check from scratch 111  Preventing Check Forgery Chemically sensitive paper Large font size requires more ink and makes alterations more difficult High resolution borders that are difficult to copy Multiple color patterns Embed fibers that glow under different light Use chemical wash detection systems that change color when a check is altered 112  Literary Forgery Best forgeries aim to duplicate the materials found in the original: – old paper – chemically treated materials to fake an older look – inks mixed from substances that would have been used at the time – watermarks that add the appearance of age – tools and styles that would have been popular at the time 113  Security Printing Currency – Counterfeiting of money is one of the oldest crimes – $20 bill is the most commonly counterfeited U.S. banknote – Bills with new features are being introduced to hinder counterfeiting: Color-shifting ink Watermark Polyester thread Microprinting  Security Printing Canadian currency – The Canadian Journey series of banknotes was issued in 2001. – It includes enhanced security features. – It also includes a tactile feature to help visually impaired people identify different denominations.  Counterfeiting A criminal activity existing since antiquity Items commonly forged today include: – Currency – Traveler’s checks – Food stamps – Certain bonds – Postage stamps 116  Counterfeit Currency Security features are added to paper currency that scanning cannot reproduce Regular printer paper contains starch. Paper currency contains rag fiber instead of starch. 117 Counterfeit vs. Authentic 118  Verifying Authentic Currency New security features: 1. Portrait stands out and appears raised off the paper 2. Contains clear red and blue fibers woven throughout the bill 3. Has clear, distinct border edges 4. Treasury seal is shown with clear, sharp saw-tooth points 5. Watermark appears on the right side of the bill in the light 119  Verifying Authentic Currency New security features: 6. The security thread is evident—a thin embedded vertical strip with the denomination of the bill printed in it 7. There is minute printing on the security threads, as well as around the portrait 8. When the bill is tilted, the number in the lower right- hand corner makes a color shift from copper to green 120 Examples of Security Features 121 Figure 7-18  Paper Measurable features of paper – Color – Weight – Brightness  Paper Nondestructive tests – Visual comparison of questioned document to different types of paper: observe differences – Micrometer: measure thickness – Inspection for watermarks: may reveal when the paper was produced and by which manufacturer  Paper Destructive tests – Chemical testing can associate or dissociate a questioned document with a known standard. – Fillers are often added to make paper’s surface more attractive and bright. – Examination of the surface of the sheet by either scanning electron microscopy with energy- dispersive X-ray (SEM-EDX) or X-ray diffraction will reveal the elements present on the surface.  Security Printing Screen printing: a nylon screen is stretched across an open box frame, and a stencil is placed over it Letter press printing: a design is raised from the surface and ink is applied only to the raised area Lithography: a design is painted on a printing plate and rolled onto paper Intaglio: an image is carved onto a metal printing plate  Identity Documents Passports are popular targets for forgers. – Many countries are adding new security features to their passports to prevent forgeries. – Eventually all U.S. passports will include a radio- frequency identification (RFID) chip containing a duplicate of the information printed on the passport pages. In the future, biometrics (retina scans, etc., think like Minority Report) will likely be used to verify someone’s identity  Identity Documents US-VISIT: U.S. Visitor and Immigrant Status Indicator Technology – The program uses the IDENT computer network, which requires travelers to have prints of both index fingers taken at a consulate or embassy overseas. – When visitors arrive in the United States, IDENT scans their fingers and verifies the information from the previous entry.  Identity Documents US-VISIT – The IDENT system has been criticized because it does not link to the FBI database. – This omission might allow terrorists to slip into the United States.  Testimony of Document Examiners Has been accepted in courts for 100 years 1989: article challenged the use of expert handwriting testimony United States v. Starzecpyzel (1995): court ruled that document examiners provide technical (not scientific) testimony 1997: study found that trained document examiners were more proficient than nonexperts United States v. Paul (1999): upheld the use of expert handwriting testimony and the exclusion of the testimony of a person without specific training in document examination  Erasures, Obliterations, and Alterations Optical analysis of ink – Infrared luminescence can be used to find alterations that were made with different ink. The document can be illuminated with near-infrared light and its image examined sequentially through a series of optical filters. The document can be illuminated with intense visible light that has been filtered to be free of near-infrared radiation and fluoresces as a result.  Erasures, Obliterations, and Alterations Optical analysis of concealed information – If the masking ink is transparent to near-infrared light and the underlying ink is opaque, the examiner may use infrared light and an infrared filter to show concealed information. – If the masking ink is slightly transparent to visible light and the underlying ink is fluorescent, the examiner may use intensive visible light to illuminate the document. – If the masking ink is fluorescent and the underlying ink absorbs the fluorescence, the examiner may study the document under intense visible light. Figure 7-9  Erasures, Obliterations, and Alterations Chemical analysis of ink – The most common chemical technique used to analyze ink is thin-layer chromatography. – An ink sample is collected by taking small “punches” from a portion of the written line in question. – The ink is extracted from the paper by adding a drop of pyridine (or other solvent). – Some ink manufacturers have added “tags” to their inks that identify the manufacturer and year of production of the ink.  You likely did thin-layer chromatography (TLC) in elementary or middle school with markers The ink separates into different bands that make up the final color we see................. Summary Handwriting analysis compares questioned documents with exemplars to establish authorship. Aspects of a person’s handwriting style can be analyzed to ascertain authenticity. Many new features of paper currency help prevent counterfeiting. Technological advances have enhanced chances of detecting forged documents. 137  DNA Deoxyribose nucleic acid (incase you forgot)  Introduction The DNA in all cells of an individual is the same through the body. DNA contains repeated sequences of genetic codes with core sequences that are unique to particular individuals. The genetic code can be determined from a small amount of DNA.  Introduction James Watson and Francis Crick made the landmark discovery in 1953 of the structure of DNA and its method of replication In 1983 Alec Jeffreys found that DNA contained repeated sequences of genetic codes Jeffreys discovery was crucial in the development of the technology known as the DNA fingerprint – DNA first used in a criminal case in Leicester, England in the late 1980’s  Restriction Fragment Length Polymorphisms DNA contains genes that control production of proteins in the body. Other sections act as spacers between the coding areas. – The sequences of bases in the noncoding regions are used for DNA profiling. – The sequences vary greatly from person to person.  History of Biological Evidence in Forensics DNA fingerprinting – Also known as DNA profiling – Used with a high degree of accuracy Biological evidence is examined for the presence of inherited traits Some forensics laboratory techniques were originally developed for other purposes. Can you name any? 142  The Function and Structure of DNA DNA contains the genetic material of a cell Chromosomes are located in the cell nucleus Chromosomes contain long DNA strands wrapped around proteins 143  The Function and Structure of DNA Nitrogenous Bases—pairs of molecules that form the rungs of the DNA “ladder” Four types of Bases – A (adenine) – C (cytosine) – G (guanine) – T (thymine) 144  The Function and Structure of DNA Base-Pairing Rules – adenine (A) binds only with thymine(T) – Cytosine (C) binds only with guanine (G) 145  DNA Identification Polymorphisms: Non-coded DNA that contain unique patterns of repeated base sequences that that are unique to individuals DNA Fingerprinting (Profiling) isolates and analyzes polymorphisms DNA fingerprints appear as a pattern of bands on X-ray film. 146  DNA Profile Two types of repeating DNA sequences Variable Numbers of Tandem Repeats (VNTR) – The number of repeats varies from person to person – 9 to 80 bases in length Short Tandem Repeats (STR) – 2 to 5 bases in length – Shorter lengths make STRs easier to use than VNTRs VNTR and STR data are analyzed for – tissue matching – inheritance matching 147  DNA Profile Matching Tissue Matching – Two samples that have the same band pattern are from the same person Inheritance Matching – Each band in a child’s NDA fingerprint must be present in at least one parent 148  DNA Population Databases Population genetics: – the study of gene variations among groups of individuals – Analyze the probability of a random person with the same alternative form of a gene (an allele) Examples – Identifying the suspect in a crime – Identifying an alleged father in a paternity case 149  Sources of DNA Biological evidence: examples include saliva, blood, skin, hair, seminal fluid Individual evidence is capable of identifying a specific person. Small amounts may be only trace evidence Polymerase chain reaction (PCR) technique generates multiple copies of DNA evidence 150  Polymerase Chain Reaction: A DNA Copy Machine Advantages of PCR – Allows many copies of a portion of DNA sequence to be manufactured in the DNA lab – Amplifies only those DNA regions that are of interest – Is fast and extremely sensitive  Collection and Preservation of DNA 1. Use disposable gloves and collection instruments 2. Avoid physical contact, talking, sneezing, and coughing in the evidence area 3. Air-dry evidence and put it into new paper bags or envelopes 4. Dry or freeze the evidence 5. Keep evidence cool and dry during transportation and storage 152  Preparing DNA Samples for Fingerprinting 1. DNA is mixed with special enzymes 2. Enzymes cut apart the DNA in specific places forming different sized fragments 3. DNA is separated within an agarose gel 4. An electric current is passed through the gel separating the fragments by size 153  Preparing DNA Samples for Fingerprinting Extraction 1. Cells are isolated from biological evidence such as blood, saliva, urine, semen, and hair 2. The cells are disrupted to release the DNA from proteins and other cell components 3. The DNA can be extracted from the cell nucleus 154  Preparing DNA Samples for Fingerprinting Amplification VNTR analyses—polymerase chain reaction (PCR) can be used to amplify the DNA that contains the VNTRs STR profiles—restriction enzymes are unnecessary; PCR allows the amplification of the strands with STR sequences 155  Preparing DNA Samples for Fingerprinting Electrophoresis DNA samples are placed in gels through which electronic currents are passed DNA fragments line up in bands along the length of each gel 156  Electrophoresis An electrophoresis apparatus running five sample of DNA Arrows show the movement of the negatively charged DNA fragments through the gel matrix 157  Probes DNA probes – identify the unique sequences in a person’s DNA – are made up of different synthetic sequences of DNA bases complimentary to the DNA strand – bind to complimentary bases in the strand (see the fragmentary DNA bands above) In most criminal cases, 6 to 8 probes are used 158  Analysis of DNA Fingerprints and Applications Bands and widths are significant in matching samples of DNA 159  Analyzing the STR by Electrophoresis Electrophoresis – Causes ions in solution to migrate under the influence of an electric field – Separates STRs according to their length: smaller DNA molecules move faster – Establishes the number of repeats and elucidates the genotype of the individual at each amplified locus  Analyzing the STR by Electrophoresis Gel electrophoresis – After voltage is applied 2–3 hours, electrophoresis stops and the DNA is made visible. – Each group of similar-length molecules appears as a narrow band in the gel. – By comparing the locations of the bands in each sample lane to the ladder, the technician can determine the STR type for each sample. – Gel electrophoresis is slow, is difficult to automate, and can be dangerous. Figure 14-7  Analyzing the STR by Electrophoresis Capillary electrophoresis – Allows for greater heating than is possible with a slab gel – Uses a higher voltage, so molecules migrate much faster – Produces high-speed, high-resolution separations on extremely small samples – Uses laser fluorescence: fluorescent dye is attached to the PCR primer that amplifies the STR region of interest  Analysis of DNA Fingerprints and Applications DNA fingerprinting can – match crime scene DNA with a suspect – determine maternity, paternity, or match to another relative – eliminate a suspect – free a falsely imprisoned individual – identify human remains 164  CODIS Combined DNA Index System – Created in 1994 as part of the DNA Identification Act – Consists of a national database containing the DNA of individuals convicted of sexual and violent crimes – Assisted in 20,000 investigations in 2004  CODIS Three tiers of CODIS – Local: labs maintain a local DNA index – State: combines the profiles of all local labs – National: compares profiles of all state systems  CODIS All 50 states maintain databases for sexual offenders and convicted murderers 49 states include violent felons 43 states include all felons  CODIS Use of CODIS – The computer compares the DNA profile submitted with profiles on file in the network. – If a match is found in the Convicted Offender Index, the lab is sent the identity of the perpetrator. – If a match is found in the Forensic Index, two crimes have been linked together. The labs must then verify the match; law enforcement may then pool resources to solve the crimes. Figure 14-16  Interpretation of DNA Profiles It is easier to use DNA to exclude a person from suspicion than to prove that the person is the only suspect. The Innocence Project reports that three times more suspects are proven innocent by DNA analysis than are proven guilty. The loci used for DNA matches must be chosen to minimize the chance that two people will have the same profile.  Paternity Testing A child can receive only one of the father’s alleles and one of the mother’s alleles. A familial pattern should be obvious by comparing the DNA profiles of mother, father, and child.  Paternity Testing Paternity index: the likelihood that an allele from the child supports the assumption that the tested man is the true biological father Combined paternity index: determined by multiplying the individual PIs for each locus tested  Mitochondrial DNA Analysis Examination of recovered mitochondrial DNA is useful in circumstances of badly decomposed or burned bodies, old bones, and human hair without follicular tags mtDNA is rarely used in criminal proceedings. It has been useful for historical investigations.  Mitochondrial DNA Analysis Mitochondrial DNA (mtDNA) – Is a circular DNA molecule that is only 16,569 pairs in circumference – Has no noncoding elements; every base has a function – For the most part, is the same in all individuals  Mitochondrial DNA Analysis Variations in mtDNA – The D-loop contains two hypervariable regions whose sequences vary. – A difference of less than 3% is expected between unrelated individuals.  Mitochondrial DNA Analysis DNA sequencing: determines the sequence of bases along a DNA strand Anderson sequence: the first mtDNA hypervariable sequence to be determined; serves as a reference sample  Mitochondrial DNA Analysis mtDNA is inherited from a person’s mother. All brothers and sisters of the same mother have the same mtDNA, which is also the same as the mtDNA of their maternal grandmother and their mother’s siblings............... Summary.... DNA contains the information needed for replication in a sequence of nitrogenous bases. DNA analysis allows even a small sample of tissue to be identified with a single individual. DNA contains, in non-coding regions called junk DNA, many repeated sequences that vary in number between individuals. These differences between individuals can be used to produce a DNA fingerprint for an individual. 178................. Summary Polymerase chain reaction (PCR) for DNA amplification has largely eliminated the problem resulting from the tiny samples usually available. DNA evidence must be collected carefully to avoid contamination with other DNA. DNA analysis involves extraction, electrophoresis, and visualization. DNA profiles are kept by police agencies in electronic databases. 179  Blood Spatter patterns, typing, etc.  Blood Blood is a mixture of cells, proteins, enzymes, and inorganic salts Plasma: the liquid portion of blood – Accounts for 55% of the total blood volume – Consists of 90% water and 10% dissolved materials  Introduction and History Blood typing provides class evidence DNA profiling provides individual evidence A blood spatter pattern provides information – the truthfulness of an account by a witness or a suspect – the origin of the blood – the angle and velocity of impact – the type of weapon used 182  Blood Cellular components of blood – Account for 45% of the total blood volume – Include three major types Erythrocytes: red blood cells Leucocytes: white blood cells Thrombocytes: platelets  Composition of Blood Plasma—a liquid suspending other blood components Red blood cells (Erthrocytes)—carries oxygen to the body’s cells and carbon dioxide away White blood cells (Leukocytes)—fights disease and foreign invaders and, alone, contain cell nuclei Platelets—aids in blood clotting and the repair of damaged blood vessels 184  Tests for the Presence of Blood Police want to answer three questions: – Is this blood? – Is it from a human? – How closely does it match the blood of the victim or the suspect?  Tests for the Presence of Blood Presumptive tests for blood are presumptive because they detect not only blood, but other substances that can give a false positive – Luminol: sprayed directly on bloodstained object; produces a glow when it contacts blood – Luminol does not degrade DNA, nor does it interfere with any subsequent testing that may follow Figure 13-2  Tests for the Presence of Blood Kastle-Meyer test – Also known as phenolphthalein – Positive test for blood turns a bright pink color Leuchomalachite Green test – Positive test for blood turns a blue-green color  Tests for the Presence of Blood Serological tests for blood: precipitin serological test – Determines if blood is of human origin – Can be used with antiserum prepared for other animals if it is negative for human blood – Requires only a small blood sample – May produce a positive result even if bloodstains were washed down to a tiny sample remaining – Is highly sensitive even when bloodstains are odd  Tests for the Presence of Blood Serological blood typing – ABO system: separates human blood into four broad classifications based on the presence or absence of the antigen A or antigen B on the surface of red blood cells – Rh factor: expressed as positive or negative – Today, DNA profiling has superseded this approach to blood testing  Tests for the Presence of Blood Because blood type is inherited from parents, blood types tend to concentrate among certain ethnic groups – A blood type is most common in Caucasians and those of European decent – B blood type is most common among African-Americans and certain Asians (Thai) – AB blood type is most common in Japanese and Chinese populations – O blood type is most common among ingeneous people (Aborigines and Native Americans) and Latin Americans Table 13-1  Tests for the Presence of Blood Because blood types are inherited from a person’s parents, blood types may become concentrated among certain ethnic groups. 80% of the population are secretors—they have significant concentrations of antigens in other body fluids. Cellular Components of Blood 194  Blood Typing—Proteins Discovered in 1900 by Karl Landsteiner Identifies the presence or absence of particular proteins embedded in the cell Quicker and less expensive than DNA profiling Produces class evidence but can still link a suspect to a crime scene or exclude a suspect 195  Blood Typing—Proteins 42% 12% 3% 43% of the population in the United States 196  Rh Factor 85% of the population has a protein called RH factor on their blood cells 197  Blood Typing—Antibodies Antibodies are Y-shaped proteins secreted by white blood cells that attach to antigens to destroy them Antigens are foreign molecules or cells that react to antibodies 198  Blood Enzymes Enzymes are complex proteins that catalyze different biochemical reactions Many enzymes and proteins have been found in the blood that are important for identification purposes 199  Blood Typing —Probability and Blood Types The probability of a blood type equals the product of probabilities for each protein group If Type A = 42% and Rh Factor = 85% Then A+ =.42 x.85 =.357 (35.7%) Knowing additional proteins and enzymes in the blood sample – Narrows the population group – Increases the probability of identifying a suspect 200  Tests for the Presence of Blood Other blood typing systems: based on the presence of proteins in red blood cells – Polymorphic proteins occur in multiple forms. – Different forms can be identified and their statistical occurrence in the population calculated. – The more independent factors that can be identified in a blood sample, the smaller the percentage of the population possessing that combination of blood traits.  Blood Spatter 1939—spatter patterns first analyzed Blood may spatter when a wound is inflicted Blood spatter pattern—a grouping of blood stains Patterns help to reconstruct the events surrounding a shooting, stabbing, or beating 202  Blood Spatter Analysis Analysis of a spatter pattern can aid in determining the: – direction blood traveled – angle of impact – point of origin of the blood – velocity of the blood – manner of death 203  Blood Spatter Analysis Natural cohesiveness of blood (hydrogen bonding) 204  Blood Spatter Analysis Satellite droplets— – When blood falls from a height, or at a high velocity, – It overcomes its natural cohesiveness, and – Separates from the main droplet Spiking patterns— – Form around the droplet edges when blood falls onto a less-than-smooth surface 205  Blood Spatter Analysis —Directionality The shape of an individual drop of blood provides clues to the direction from where the blood originated. How will the point of impact compare with the rest of a blood pattern? 206  Blood Spatter Analysis Lines of convergence—two or blood splatters can pinpoint the location of the blood source 207  Blood Spatter Analysis —Six Patterns Describe each of these: a) Passive drops b) Arterial gushes c) Splashes d) Smears e) Trails f) Pools 208  Blood Spatter Analysis —Impact Patterns can help investigators determine the type of weapon used What kind of a pattern is produced by a gun shot? What kind of a pattern is produced by a hammer blow? 209  Crime Scene Investigation of Blood 1. Search for blood evidence 2. Determine a. Is the evidence blood? b. Is the blood human? c. What is the blood type? 3. Interpret the findings: a. Does the blood type match a suspect’s blood? b. If not, exclude that suspect c. If yes, decide if DNA profiling is necessary 210................. Summary Blood consists of cellular components and plasma. The various human blood types are caused by the presence or absence of A and/or B proteins on the surface of red blood cells. Blood spatter evidence can be used to recreate a crime scene. Investigators endeavor to (a) locate, (b) identify, and (c) interpret blood splatter patterns at crime scenes. 211