Criminal Investigations: Forensics and Physical Evidence

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Questions and Answers

What is the main objective of maintaining the chain of custody?

To determine the relevance of evidence

To ensure the integrity of evidence from discovery to disposal (correct)

To prevent contamination of evidence

To identify the type of physical evidence

What is the term for evidence that serves to establish or prove a fact?

Probative evidence (correct)

Indirect evidence

Relevant evidence

Circumstantial evidence

What is the term for the impressions or marks left by a firearm?

Caliber

Rifling (correct)

Bore

Tool mark

What is the term for evidence that is obtained from a person, place, or thing?

Material evidence Signup and view all the answers

What is the term for the process of comparing a suspect's fingerprints with fingerprints found at a crime scene?

AFIT Signup and view all the answers

What is the term for the phenomenon where people's expectations of forensic science are influenced by popular media?

CSI effect Signup and view all the answers

What is a CSI responsible for?

Developing, processing, and packaging physical evidence found at the crime scene Signup and view all the answers

What has contributed to the general public's increased familiarity with forensic technology?

Using consumer-level technology Signup and view all the answers

Why is it helpful for investigators to contact other law enforcement agencies when selecting equipment?

To identify what equipment is needed for their organization Signup and view all the answers

What is a mobile crime lab typically equipped with?

A specially equipped van with equipment to process most crime scenes Signup and view all the answers

Why do most failures during equipment use occur?

Due to lack of training given to those using it Signup and view all the answers

What is the purpose of cordoning off the crime scene?

To prevent contamination of evidence Signup and view all the answers

What is referred to as the 'chain of evidence'?

The documentation of what has happened to the evidence from discovery to court Signup and view all the answers

What can result in the loss of evidence value?

Improper collection, handling, or identification of evidence Signup and view all the answers

What is Locard's principle of exchange?

The principle of exchange of material between two surfaces that come into contact Signup and view all the answers

What is important to consider when recognizing evidence at a crime scene?

Objects unrelated or foreign to the scene, unusual in location or number, or damaged or broken Signup and view all the answers

What is the primary goal of forensic science in the context of the criminal justice system?

To solve legal problems Signup and view all the answers

What type of evidence is considered the most reliable in a court of law?

Best evidence Signup and view all the answers

What is the term for extremely small items, such as hair or fibers, that are used as evidence?

Trace evidence Signup and view all the answers

What is the primary purpose of associative evidence?

To link a suspect with a crime Signup and view all the answers

What is the FBI Handbook of Forensic Services primarily used for?

Crime scene safety Signup and view all the answers

What is the primary advantage of disposing of evidence through auction sites like Property Room?

It reduces the burden of unclaimed property on police departments Signup and view all the answers

What is the primary goal of the DNA Initiative Office of Justice Programs?

To provide training on DNA analysis Signup and view all the answers

What is the term for evidence that has been properly collected, identified, filed, and continuously secured?

Competent evidence Signup and view all the answers

What is the primary purpose of hair evidence in a criminal investigation?

To link a suspect to a crime scene Signup and view all the answers

What is the term for evidence that applies to the matter in question?

Relevant evidence Signup and view all the answers

What type of characteristics are used to place an item into a specific category?

Class characteristics Signup and view all the answers

Where are latent prints typically found?

Nonporous surfaces Signup and view all the answers

What is the purpose of dusting latent fingerprints?

To develop the prints using powders Signup and view all the answers

What is the advantage of using Microbeam X-ray fluorescence (MXRF) in fingerprint analysis?

It rapidly reveals the sample's elemental composition Signup and view all the answers

How many matchable characteristics are required for positive identification in a single fingerprint?

12 Signup and view all the answers

What is the primary purpose of forensic light sources in investigations?

To make evidence visible that is not otherwise detectable to the naked eye Signup and view all the answers

What is the primary reason for managing evidence and property?

To accommodate the increasing quantity of evidence that must be stored for longer periods Signup and view all the answers

What is the term for the graphic record of the energy patterns emitted by speech?

Voiceprint Signup and view all the answers

What is the purpose of marking or identifying each item of evidence?

To ensure that the evidence can be recognized later Signup and view all the answers

What is the study of the mental processes involved in comprehending, producing, and acquiring language?

Psycholinguistics Signup and view all the answers

What is the building block of chromosomes that is unique to an individual?

DNA Signup and view all the answers

What is the term for an object, measure, or model with which evidence is compared to determine whether both came from the same source?

Standard of comparison Signup and view all the answers

What is the term for the process of creating a genetic fingerprint to positively identify a person?

DNA profiling Signup and view all the answers

What is the primary purpose of a TracER system?

To recover trace evidence Signup and view all the answers

What type of evidence can be captured using digital recorders?

Language analysis evidence Signup and view all the answers

What is the primary purpose of exhibiting evidence in court?

To ensure admissibility of evidence Signup and view all the answers

What is the primary purpose of packaging and preserving evidence?

To ensure the integrity of the evidence Signup and view all the answers

What is the primary purpose of the Frye and Daubert cases?

To ensure the admissibility of scientific evidence in court Signup and view all the answers

What is the primary purpose of the final disposition of evidence?

To legally dispose of evidence when the case is closed Signup and view all the answers

What is the primary purpose of accrediting forensic laboratories?

To ensure the reliability of the testing process Signup and view all the answers

What is the main advantage of using DNA evidence in high-volume crimes such as burglaries and car break-ins?

It can aid in solving crimes with a low cost per test Signup and view all the answers

What is the purpose of using sterile, cotton-tipped applicator swabs to collect DNA samples?

To collect four DNA samples by rubbing the inside surfaces of the cheeks Signup and view all the answers

What is the difference between nuclear DNA (nDNA) and mitochondrial DNA (mtDNA)?

nDNA is found in blood and saliva, while mtDNA is found in hairs and bones Signup and view all the answers

What is the limitation of Y-STR analysis?

The DNA profile obtained will be identical for all males within the same paternal lineage Signup and view all the answers

What is the purpose of Biogeographical Ancestry DNA testing?

To include or exclude certain people from an investigation based on their ancestry Signup and view all the answers

What is the name of the DNA database that contains profiles from crime scene evidence and convicted offenders?

CODIS Signup and view all the answers

What has been the trend of the year-end backlog of offender DNA samples in the US?

It has increased steadily Signup and view all the answers

What is the significance of DNA evidence in court?

It can identify a criminal with near absolute certainty Signup and view all the answers

How many people had been exonerated through DNA testing as of the time this text was written?

325 people Signup and view all the answers

What is unique to every person and can be used as evidence?

Scent Signup and view all the answers

What type of evidence can be used to place an individual at a crime scene?

Hairs and fibers Signup and view all the answers

What technique can distinguish trace hair samples using consumer chemicals as identifiers?

Secondary ion mass spectrometry (SIMS) Signup and view all the answers

What type of evidence can be found on the suspect or victim’s body or on objects placed in the mouth?

Bite marks Signup and view all the answers

What is the name of the database that contains over 700 glass samples from manufacturers, distributors, and vehicle junkyards?

Glass Evidence Reference Database Signup and view all the answers

What type of evidence can be used to identify a suspect and can also be a source of genomic DNA?

Teeth Signup and view all the answers

What type of evidence can be compared by type or cut ends?

Ropes, strings, and tapes Signup and view all the answers

What type of evidence can be used to make a preliminary analysis of a suspicious substance?

Drug identification kits Signup and view all the answers

What type of evidence can be used to identify a safe's insulation?

Safe insulation Signup and view all the answers

What is a major challenge in collecting digital evidence?

Absence of geographic boundaries and jurisdictional issues Signup and view all the answers

What is the first step in collecting evidence from a cell phone?

Do not change the condition of the evidence Signup and view all the answers

Who should analyze a cell phone in an investigation?

A person with training Signup and view all the answers

What is the purpose of a Global Positioning System (GPS) chip in a cell phone?

To track a cell phone's location Signup and view all the answers

What type of records do cell phone providers store and maintain?

Subscriber information and call-detail records Signup and view all the answers

What is the primary concern at a Weapons of Mass Destruction (WMD) crime scene?

Public safety Signup and view all the answers

How can laboratories determine whether skeletal remains are animal or human?

Through dental comparisons and X-rays of old fractures Signup and view all the answers

What can be examined and compared in wood evidence?

The type of wood and origin Signup and view all the answers

What is the importance of learning to read 'product DNA'?

To provide valuable leads in an investigation Signup and view all the answers

What precautions should investigators take when collecting blood evidence?

Use universal precautions Signup and view all the answers

What should investigators do when handling bodily fluids and other potentially infectious materials?

Wash hands thoroughly with soap and water Signup and view all the answers

What happens to evidence when it is no longer needed?

It is auctioned off, returned to the owner, or destroyed Signup and view all the answers

Study Notes

Forensic Science and Physical Evidence

Forensic science is the application of scientific processes to solve legal problems, notably within the context of the criminal justice system.
Crime scenes always leave behind incriminating evidence, known as proxy data.

Types of Evidence

Best evidence: original evidence
Physical evidence: anything with substance that helps establish the facts of a case
Direct evidence: establishes proof of a fact without other evidence
Indirect evidence (circumstantial evidence): tends to incriminate a person
Trace evidence: extremely small items, such as hair or fibers
Prima facie evidence: evidence established by law
Associative evidence: links a suspect with a crime (e.g., fingerprints, footprints, bloodstains, hairs, and fibers)
Corpus delicti evidence: establishes that a crime has been committed
Probative evidence: vital to the investigation or prosecution of a case
Material evidence: forms a substantive part of the case
Relevant evidence: applies to the matter in question
Competent evidence: properly collected, identified, filed, and secured

Crime Scene Investigators (CSIs)

CSIs develop, process, and package physical evidence, transport it to the lab for forensic evaluation, attend and document autopsies, and write reports and testify in court.
The CSI effect: a phenomenon that has created a glamorized, impractical image of the field.
The tech effect: public awareness of modern technology influencing juror expectations.

Investigative Equipment

Equipment needed for each type of investigation varies.
Specialized equipment includes cameras, chalk, containers, fingerprint kits, labels, magnifiers, measuring tape, notebooks, pens, and laptops.
Selecting equipment:
- Work with other organizations to identify needs.
- Select equipment based on organizational needs.
Equipment containers:
- Use professional containers and equipment to create a consistent image.
- Care for equipment to ensure it works when needed.
Transporting equipment:
- Use police cars, specially equipped vehicles, or mobile crime labs.
Training in equipment use:
- Lack of training is a common cause of equipment failure.

Crime Scene Integrity and Contamination of Evidence

The value of evidence is directly affected by what happens to it immediately following the crime.
Cordon off the crime scene to maintain integrity.
Document everything: what has happened to the evidence from discovery to the present.
Recognize potential evidence:
- Examined objects unrelated or foreign to the scene.
- Unusual items in location or number, or damaged or broken objects that fit a pattern that suggests a crime.

Processing Evidence: Maintaining the Chain of Custody

Discovering or recognizing evidence:
- Consider the type and nature of the crime.
- Examine objects in the area of the crime scene.
- Recall the Brady rule: gather all evidence that helps establish guilt or innocence.
Marking, identifying, and collecting evidence:
- Mark or identify each item of evidence in a way that can be recognized later.
- Record the date and time of collection, where the evidence was found, and by whom.
- Package each item separately in a durable container.
Transporting evidence:
- Use registered mail, insured parcel post, air express, or Federal Express.
- Specify that the person receiving the evidence is to sign for it.
Protecting and storing evidence:
- Store evidence in a secure, pest-free, and climate-controlled environment.
- Manage property effectively to accommodate the increasing amount of evidence.

Frequently Examined Evidence

Biometrics: the statistical study of biological data.
Fingerprinting:
- Latent prints: not readily seen, developed through powders or chemicals.
- Visible fingerprints: made when fingers are dirty or stained.
- Plastic fingerprints: impressions left in soft substances.
- Dusting latent fingerprints: be careful not to over-process.
- Lifting prints: use black lifters for light powders and light lifters for dark powders.
Voiceprints:
- Graphic record of the energy patterns emitted by speech.
- Like fingerprints, no two voiceprints are alike.
DNA Profiling:
- Deoxyribonucleic acid (DNA) is the building block of chromosomes.
- Genetic code can be used to create a genetic fingerprint to positively identify a person.### DNA and Forensic Analysis
The national backlog of offender DNA samples increased from 657,166 in 2007 to 952,393 in 2009.
DNA can identify a criminal with near absolute certainty or exonerate innocent suspects.
As of the time the text was written, 325 people had been exonerated through DNA testing.

Biological Evidence

Blood and other body fluids, including semen and urine, can provide valuable information.
Semen and saliva can be detected with fluorescent lights.
Blood trails or blood "spatter" can be useful as evidence.
Every person has a unique scent that cannot be masked or eliminated.
Hairs and fibers can place an individual at the crime scene, especially in violent crimes.
Secondary ion mass spectrometry (SIMS) can distinguish trace hair samples using consumer chemicals as identifiers.

Shoe and Tire Impressions

Tracks or marks left by shoes or tires can be specific to the shoe or tire.

Bite Marks

Bite marks can be found on the suspect or victim's body or on anything else placed in the mouth.
Bite mark identification is based on the individuality of teeth and is legally admissible in court.
Teeth may also be an excellent source of genomic DNA.

Tools and Tool Marks

Tools can be traced if broken parts are left behind or by marks caused by the use of the tool.

Firearms and Ammunition

Gunpowder tests, shot pattern tests, and functional tests of a weapon can be made and compared.
Firearm evidence can include bullets, shell casings, slugs, shot pellets, and gunshot residue.

Glass Evidence

Glass can be used for transfer of evidence and to show where a piece of glass came from at the crime scene.
The Glass Evidence Reference Database contains more than 700 glass samples from manufacturers, distributors, and vehicle junkyards.

Soils and Minerals

Soil and mineral analysis can place a suspect at a crime scene.

Other Types of Evidence

Safes contain insulation that can transfer to the suspect's clothing.
Ropes, strings, and tapes can be compared, either by type or the cut ends.
Drug identification kits can be used to make a preliminary analysis of a suspicious substance.
Documents, such as typing, handwriting, and printing, can be compared.
Laundry and dry-cleaning marks can be used for comparisons and to find the business.
Paint colors and samples can lead to the identification of an automobile.
Digital evidence, such as cell phones, pagers, and computers, can generate a new class of evidence.
Each cell phone provider stores and maintains subscriber records, including subscriber information and call-detail records.
Global positioning system (GPS) chips built into cell phones allow authorities to track criminals.

Weapons of Mass Destruction (WMDs)

Testing matrixes include aerosols, liquids, solids, surfaces, and dermal samples.
At any WMD crime scene, the public's safety takes precedence over evidence collection.

Skeletal Remains

Laboratories can determine whether skeletal remains are animal or human.
Dental comparisons and X-rays of old fractures are other important identifying features.

Wood and Other Types of Evidence

Wood comparisons are possible regarding the type of wood and origin.
Prescription eyeglasses, broken buttons, glove prints, and other personal evidence found at a crime scene can also be examined and compared.

Evidence Handling and Infectious Disease

All body secretions should be considered as potential health hazards.
AIDS is not spread through casual contact.
Tuberculosis (TB) is of greater concern.
MRSA is a staph infection that is resistant to most antibiotics and is very infectious, severe, and sometimes deadly.
Universal precautions should be used when collecting blood evidence and other bodily fluids.
Hands should be washed thoroughly with soap and water.

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Description

This quiz covers the basics of forensic science and physical evidence in criminal investigations. Topics include crime scene integrity, evidence handling, and maintaining the chain of custody.