Forensic Chemistry and Toxicology PDF

**FORENSIC3: INTRODUCTION OF FORENSIC CHEMISTRY AND TOXICOLOGY** **Forensic** denoting the application of scientific methods and techniques to the investigation of crime. **Chemistry** is a branch of science that deals with the study of matter, phases it undergoes, and energy that accompanies in e...

**FORENSIC3: INTRODUCTION OF FORENSIC CHEMISTRY AND TOXICOLOGY** **Forensic** denoting the application of scientific methods and techniques to the investigation of crime. **Chemistry** is a branch of science that deals with the study of matter, phases it undergoes, and energy that accompanies in every changes. **Forensic chemistry** is the analytic study of substances that could easily be misidentified or confused, and finding their identity. **Forensic chemists** analyze the physical and chemical properties of different materials in order to identify them correctly where one or more materials may have similar properties.(who practices forensic) **ROLE OF FORENSIC CHEMIST IN THE SCIENTIFIC CRIMINAL INVESTIGATION** Forensic chemist plays important role in the scientific criminal Investigation; he may be called upon to aid an investigation In; - Determining whether or not a place/location is a clandestine laboratory. - Examination of marked bills/suspect during entrapment operation in cases of extortion. - Administering paraffin test. **Scope of Forensic Chemistry** - It includes the chemical side of criminal investigation - It includes the analysis of any material in the quality of which may give the raise of legal proceedings. - It is not limited to purely chemical questions involves in legal proceedings. - It invaded other branches of forensic science, most notably, legal medicine, ballistics, questioned documents, dactyloscopy, and photography. **Four Stages of a Forensic Chemist Work** **Six Golden Rules in the Practice of Forensic Chemistry** 1\. Go slowly 2\. Be thorough 3\. Take notes **Physical Evidence** refers to articles and materials found in connection with an investigation and which aid in establishing the identity of the perpetrator **Evidence** refers to a proof of allegation. A mean suctioned by law to ascertain in a judicial proceedings respecting a matter of fact. **Three Major Classification of Evidence** 1\. **Direct Evidence** A kind of evidence that directly establishes the main fact of issue, it may simply refer to what the senses perceive. Any fact to which the witness testifies based on what he saw, heared, smelled, touched or tasted. **2. Circumstantial Evidence** A kind of evidence that seeks to establish a conclusion by inferences from proven facts. It establishes a fact or circumstances from which the court may infer, another fact at issue. 3\. **Hearsay Evidence** Proceeds not from personal knowledge of the witness but from the mere repetition of what the witness heared from other people. A statement made by a witness on the authority of another and not from his own personal knowledge or observation. Hearsay evidence is inadmissible in court except with certain well-defined expectations, like declaration against interest, dying declaration, reputation, public records and statements made at a prior time. **Scientific Evidence** Evidence wherein scientific knowledge is necessary, based on conforming principles and techniques of science, **Forms of Scientific Evidence** 1\. **Real or Autoptic Evidence** A kind of evidence that addressed to court, it is not limited to which can be known sense of vision but extends to those which are peceive by the senses of hearing, taste, smell, and touch. 2\. **Testimonial Evidence** Expert witness may be placed on the witness stand to answer all the questions profounded by both parties in the case. This type of evidence is a declaration of truth by an expert. 3\. **Experimental Evidence** An expert witness may be required to perform experiments to prove a certain fact. 4\. **Documentary Evidence** Any written evidence presented by an expert in court that is relevant to the subject matter in dispute and not excluded by the rules of court. **WITNESS** A person, other than the suspect, who is requested to give information concerning an incident or person. He testifies in court, may be a victim, complainant, accuser, source of information, or an observer of an occurrence. **SUSPECT** is a person whose guilt is considered a reasonable grounds to be a practical possibility. A witness in court may be any of the following: 1\. **Ordinary Witness** States facts and may not express his/her opinion or conclusion and may testify to impression of common experienced. 2\. **Expert Witness** One who possessed a special skill. 3\. **Eye Witness** The person who saw the fatal act. **[BLOOD AND BLOOD STAINS]** **Blood** is called the circulating tissue of the body. It refers to a highly complex mixtures of cells, enzymes, protein, and inorganic substances. **Composition of blood** 1\. Solid portion (45%) consist of red blood cells(ERYTHROCYTES), white blood cells(LEUKOCYTE), and blood platelets(THROMBOCYTES). 2\. Liquid portion (55%) plasma. **PLASMA** yellowish fluid of blood in which numbered of blood corpuscles are suspended **SERUM** straw-yellow liquid formed when blood clotted and allow to stand for some time and the blood contracts. **PROBLEMS IN THE STUDY OF BLOOD** 1\. Where blood has to be search 2\. Collection, Preservation, packing and transportation of specimen suspected to contain blood. Blood offers little resistance to decomposition. It undergoes rapid chance in its characteristics with the passage of time as the process clotting and drying commences almost immediately. Sodium Fluoride may be added to blood to preserve it for a week at room temperature or refrigerate at the temp. Of 40-50°C **Fluid Blood is collected** 1\. Victims of violent crimes 2\. Parents and child in case of disputed parentage **Dried Blood is collected** 1\. Smooth surfaces like walls, finished floors, table tops 2. Hard surfaces like axe, hammer, knives, stones, crowbars 3\. Glaze surfaces like glass, tiles, automobiles 4\. Bulky objects like black board, linoleum sheets, doors, window frames 5\. Clothing 6\. Blood absorbed by the soil **FOUR TEST FOR BLOOD** 1\. **Preliminary Test** (Color Test) - determines whether the stain contains blood or another substance. a\. Benzidine Test (Intense Blue color) b\. Phenolpthalein Test (Deep Pink color) c\. Guaiacum Test (Beautiful Blue) d\. Leucomalachite Green Test (Bluish Green) e\. Luminol Test 2\. **Confirmatory Test** - determines if the stain really contains blood a\. Microscopic Test b\. Microchemical Test c\. Spectroscopic Test 3\. **Precipitin Test**- used to determine whether the stain /blood is of human or animal origin 4\. **Blood Groupings** The A-B-O system is used in the blood grouping of fresh blood. Lansteiner who discovered the four blood groups, namely, Group O, Group A, Group B, and Group AB. **FOUR BLOOD GROUPS** **BLOOD GROUP** **ANTIGEN/AGGLUTINOGEN ON RBC** **ANTIBODIES/AGGLUTININS IN SERUM** ----------------- --------------------------------- ------------------------------------- A A Anti B B B Anti A AB A and B Neither Anti A nor Anti B O Neither Antigen A nor Antigen B Anti A and Anti B **Phenotypes** -used to denote the expression in the inherited characteristics as found in the individual, these are actually the blood groups. **Genotype** - paired genes **Inheritance of blood groups** - are predetermined by the ***presence and absence*** of the two facts or Genes called *Gene A and Gene B.* Genes - complex chemical units in the chromosomes by which hereditary characters are transmitted. They are **responsible for the transmission of hereditary responsible for the characteristics**, they occur in pairs. There are two genes or factors called gene A and gene B, this are found in the chromosomes. **Steps in the Inheritance of Blood Groups** 1\. Write the blood group or the phenotypes of the parents 2\. Bring the group of the parents down. Say A, this contains agglutinogen A and this can be inherited as established by Dungern and Hirszfeld, and this one of the genes in the pair of genes called genotype 3\. Match the pair of genes of the parents by employing the criss-cross method to arrive the genotype of the children. 4\. Determine the dominant to determine the blood group of the children **[SEMEN AND SEMINAL STAINS]** **SEMEN** is a viscid whitish fluid of male reproductive tract consisting of spermatozoa suspended in the secretion of accessory glands. **Parts of Semen** 1\. Seminal Fluid 2\. Formed Cellular elements which includes \- Spermatozoa or sperm cell \- Epithelial cells \- Crystals of choline and \- Lecithin A *[healthy young man releases 400 to 500 million spermatozoa in a single ejaculation and 3.5 cc]* is the normal quantity of seminal fluid. Ejaculation has no Spermatozoa 1\. **Aspermia** - a condition wherein males have no spermatozoa at all in their seminal fluid. 2\. **Oligospermia** - a condition wherein males have abnormally low sperm counts or with few spermatozoa. Semen **can be found fresh** in - Vaginal contents of the victim - Rectal contents of the victim Semen **can be found as wet or dried** condition/secretion on: - Hair - Skin around genitals Semen **can be found as dry stain** on - Underclothing - Bed clothing **There are four examinations for seminal stains or seminal fluid in the form of stain:** 1.**Physical Examination** 2.**Chemical Examination** a.**Florence Test**- the only preliminary test for the presence of spermatozoa confirms the presence of seminal stains. Positive result crystals of choline. b.**Barberios Test**- almost specific for human semen it respond to seminal stain as old as 6 years old. Positive result slender yellowish, rhomboid needles with obtuse angle. c.**Acid-Phosphatase Test**- is the best way to locate at the same time characterized a seminal stain. The test replace Florence test in reliability and was shown to be specific for human and higher apes. Positive results orange-red pigment. 3\. **Microscopic examination** - to determine the presence of spermatozoa. Visible result small object with pear shaped head behind which is a short neck and a tail ten times as long as the head. *Elements which Obstruct Detection of Spermatozoa are nature of the fabric, age of the stain, condition to which the stain was exposed before reaching the laboratory, and handling of specimen.* 4\. **Biological Examination** - for persons who are \"secretors\" **Spermato-precipitin** is of value in the identification of seminal fluid in certain cases like bestiality. **Other Stains of Medico-legal Interest** 1\. Obstetrical and gynaecological stains 2\. Excrements Adults - **yellowish brown and solid** Infants - **greenish yellow** 3\. Paint stains 4\. Rust stains **Rust** - reddish brown in color, insoluble in water and soluble in diluted acid resembles to blood. 5\. Synthetic dye stains- resembles old blood stain, but can be recognize by treating strong acids and alkalis. 6\. **Mineral stains** - are due to red paints containing oxides of iron 7\. **Stain of vegetables origin** - resembles blood, they may be produced by fruit juices like mulberry and mangosten. **[GUN POWDER AND OTHER EXPLOSIVES]** In investigation of crimes involving the used of firearms, **three most important problems may arise:** 1\. Determination of whether or not a person has fired a gun with bare hands within a pertinent period of time; 2\. Determination of probable gunshot range, the distance the firearm held from the body of the victim at the time of discharge; 3\. Determination of the approximate time of firing of the gun or the approximate date of the last discharge. **2 Kinds of Gum Powder** **1.Black Powder --** consist of a mixture of charcoal or carbon 15%, sulphur 10% and potassium nitrate 75% **2.Smokeless Powder** -- consist of cellulose nitrate combined with some stabilizer. Among this stabilizers are nitrates, bicarbonates and oxalates. Organic Stabilizers are nitro benzene, graphite and Vaseline. Stabilizer is added to reduce side reactions **Possible Locations of Nitrates when Black Powder and Smokeless Powder Explode** 1\. Residue in the barrel of the gun 2\. In or around the wound 3\. On the clothing of the person fired upon at close range 4\. On the exposed surface of the hand of the person firing the ground **Factors that affect the presence and amount of** 1\. Type and caliber of the ammunition 2\. Length of the barrel of the gun 3\. Distance of the muzzle of the gun from the target 4\. Humidity 6\. Wind velocity and direction 8\. Direction of firing **Determination whether or not a person fired a gun with his bare hands** The burned residues and partially burned particles may escape around the breech of the gun and implanted on the exposed surface of the hand holding the weapon and become implanted into the skin. Test performed to determine whether a person fired a gun or not with his bare hands 1\. **Paraffin Test** - taking cast of the left hand and right hand to extract the nitrates. 2\. **Diphenylamine Test/DPA Test** - Determines the presence and distribution nitrates, the chemical aspect of the examination. Positive result deep blue specks develop when nitrates come in contact with DPA reagent. - Factors to be considered in the interpretation of DPA results are **time of reaction**, **number of blue specks**, **location of the specks**, and **character of the specks**. - Possibilities that a person may be found negative for nitrates even if he **actually fired a gun, use of automatic pistol, wind direction, wind velocity, excessive perspiration, use of gloves, and knowledge of chemicals that will remove nitrates**. - Possibilities that the person may be positive for nitrates even if he **did not actually fired a gun. It is possible that gun powder particles may have been blown on the hand directly from the barrel of the gun being fired by other person**. An attempt to shield the body by raising the hand in some instances result in the implanting of powder particles on the hand of a person close to one firing a gun. Clothing, is examined microscopically, for possible powder residues; 1\. **Singeing**-slight burning 2\. **Burring**-carbon presence 3\. **Smudging** - blacking of area around the bullet hole 4\. **Tattooing** - black coarsely peppered pattern **Distance from firearm was discharge** 0-2 inches 2-36 inches Beyond 36 inches **Characteristics Pattern** gaping hole, smudging, singeing, tattooing, burning tattooing and smudging evidence of powder tattooing is seldom present **Chemical Test for Gun Powder Residues** 1\. Method pattern after diphenylamine paraffin test 2\. Walker\'s Test - this method is used if the powder particles are deeply embedded **Determination of Probable Time when the Gun has been fired** 1\. **Rust** - if a gun has not been fired at all, no rust can be detected inside the barrel of the gun. If it has been fired, iron salts are formed and are found inside the barrel. These iron salts are soon oxidized, thus resulting in the formation of rust. 2\. **Nitrite** - determined by addition of DPA reagent blue in color. 3. Nitrate - determined by addition of diphenylamine yellow green in color. 4\. **Metallic Fragment** 5\. **Soot**-black substance that is formed by combustion. **Explosives** - any substance that may cause an explosion by its sudden decomposition or combustion. **CLASSIFICATION OF EXPLOSIVES** 1.View point of chemical composition 2\. With respect to functioning characteristics **[HAIR AND TEXTILE FIBERS]** Hair examination is one of the oldest forms of physical evidence. It is used older that of fingerprints. It is valuable because the hair of each kind of animal is different and distinct from all others. Like fibers, it is most likely to be involved in contact between the victim and suspect. Most crimes causes contact between one person and another. As such, it results in the transfer of fibers and hairs from the victim to the criminal and vice versa. The successful investigation of crimes of violence such as rape, murder, assault, kidnapping, as well as hit and run, among others, are frequently materially assisted by the result of examination of hair and fibers. **Hair is very resistant in decomposition and purification**, thus they often remain as a means of identification long after others such as facial and fingerprints have been destroyed. **Hair** - a specialized epithelial outgrowth of the skin which occurs everywhere on human body except on the palm of the hand and sole of the feet. It is an appendage of the skin. Hair is not completely round but may be oval or flattened. Its width is not always the same along its length. It strays out pointed and narrow and then strays more or less the same. **Kinds of Hair** (Among mammals including human beings) 1\. **Real Hair** - generally long and stiff 2\. **Fuzz Hair** - generally short, fine at all times curly and woody **Parts of Hair** 1\. **Root**-portion embedded in the skin 2\. **Shaft** - portion above the surface of the skin, the most distinctive part of the hair. 3.**Tip**-sometimes termed point, the distal end of an uncut hair. **Microscopic Examination of Human Hair** 1\. Color **Melanin** - the brownish black pigment in the hair and skin, among others, the chemical responsible for the color of hair. 2\. Length by actual measurement 3\. Characteristics of hair 4\. Width 5\. Characteristics of hair tip if present 6\. Manner by which hair had been cut 7\. Condition of root or base or bulb of the hair 8\. **Characteristics of cuticle**- the size, general shape and the irregularity of the scale are observed. 9\. **Characteristics if cortex** - it is embedded with pigment granules that impart hair with color. It is the color, shape and distribution of these granules that provide chemist with important points of comparison between hairs of different individuals. 10.**Presence of Dye in Hair** Dye hair can be distinguished from natural hair. Under microscope, dyed hair has dull appearance and the color tone is constant, whereas natural hair is not and the individual pigment granules stand more sharply. 11.Determination of whether naturally or artificially curled 12.Character of medulla **Medullary Index** - is the relationship between the diameter of the medulla and the diameter of the whole hair. Its determination is performed under microscope provided with micrometer eyepiece. Hair with narrow medulla less than 0.5 belongs to human, hair with medium medulla approximately 0.5 belongs to cows, horses, and others, and hair with thick medulla greater than0.5 belongs to other animals not indicated above. **Comparison between Human Hair and Animal Hair** ------------------------------------------------------------------------- -------------------------------------------- **Human Hair** **Animal Hair** 1\. M.I. is less than 0.5 M.I. more than 0.5 2\. Medulla may not be present Medulla is always present 3\. The scale pattern is fine and each one Overlaps the other more than Scale is coarse and overlaps less than 1/2 4/3 4\. Pigment granules are fine Pigment granules are coarse **Region of the Body from which Human Hair has been removed** 1\. **Scalp Hair**-they are more mature than any kind of human hair 2\. **Beard Hair**-coarse, curved, very stiff, and often in triangular in cross section 3. Hair from eyebrows, eyelid, nose, and ear - short, stubby and have wide medulla, eyebrow and eyelashes are usually very short and has a sharp tip 4\. **Trunk hair** - vary in thickness along the shaft and are immature but are somewhat similar to head hairs, they have fine, and long tip ends. 5\. **Limb Hair** - similar o trunk hair but usually are not so long or so coarse and usually contains less pigment. 6\. **Auxiliary Hair** - is fairly long with unevenly distributed pigment. They vary considerably in diameter along the shaft and have frequently a bleached appearance. It has an irregular shape and structure. Looks like pubic hair but the ends are sharper and the hair is not so curly. 7\. **Pubic Hair** - similar to axillary hair but are coarse, and do not appear bleach; more wiry, have more constriction and twist and usually have continuous broad medulla, has many broken ends because the clothing rubs. **Approximate Age of an Individual through Hair Examination** **Infant hairs** - are *fine, short in length, have fine pigment and are rudimentary in character, children\'s hair through adolescence is generally finer and more immature than adult hair but cannot be definitely differentiated with certainty*. It is noted that the pigment is missing or starting to disappear in the hair, it can be stated that the hair is from an adult. It is common for a relatively young person to have prematurely grey or white hair but not body hairs. **Textile Fibers** - fibers that can be converted into yarn **Yarn** - made of fibers which have been twisted together like a thread. **Classification of Textile Fibers** 1\. Natural Fiber 2\. Synthetic or Artificial Fiber **Test for fibers** 1\. **Burning test or ignition test** - is a simple preliminary, microscopic examination, it determines whether fiber is mineral, animal or vegetables. 2\. **Fluorescence test** - used to determine general group to which a fiber belong. It is not reliable for positive identification of fiber. 3\. **Microscopic test** - it is the most reliable and best means of identifying fibers 4\. **Chemical test** **Chemical Test for Fibers** 1\. **Staining Test** - fiber is stained with picric acid, million reagent stannic chloride or iodine solution. 2\. **Dissolution Test** - if fiber is white or light colored it is treated with the following chemicals 10% NaOH, 5 % oxalic acid, half saturates oxalic acid, concentrated oxalic acid, concentrated and diluted ammonium hydroxide and concentrated nitric acid. **Characteristics of Common Textile Fiber** 1\. **Cotton** - unicellular filament, flat, ribbon like twisted spirally to right or left on its axes, central canal is uniform in diameter. 2\. **Mercerized Cotton** - straight, cylindrical with occasional twist; unevenly lustrous, smooth except for occasional transverse folds or wrinkles and cuticle are mostly lacking. 3\. **Linen** - multicellular filament, (straight and cylindrical not twisted and flattened, tapering to a sharp point. The cell wall are thick, the lumen appearing is narrow and dark line in the center of the fibers to appear jointed resembling bamboo. 4\. **Cultivated silk**-smooth cylindrical lustrous thread, usually single but often double, the twin filament held together by an envelope of gum. They are more or less transparent, and without definite structure. 5\. **Wild silk** - similar to cultivated silk but broader and less regular in outline. Mark by very fine longitudinal striation with infrequent diagonal crpss markings. 6\. **Artificial silk**-cylindrical, lustrous, appearing like a glass rod. 7.**Wool** - easily distinguished by the presence of flattened, overlapping epidermal scales not found in silk or any of the vegetables fibers. **[QUESTIONED DOCUMENT]** **Chemical Aspects of Document Examination** **Document** - an original or official written or printed paper furnishing information or used as a proof of something else, it may refer to any object that contains handwritten or type written markings whose source or authenticity is in doubt. **Examination and Comparison of Paper** The essential materials in a document examination of any kind are the paper and ink or pencil or writings. The examination of paper may be necessary if we want to know the age of the document, presence of alterations, erasures, and other forms of forgery. **Problems Encountered in Document Examination** 1.Determination of whether two pieces of paper originated from the same source; 2.Determination the probable age of the paper; 3.Determination of the composition of paper. **Egyptian Papyrus** one of the earliest substance used for writing, derived from the name papyrus from which the paper word derived. **Composition of Paper** 1\. **Fiber Composition** - practically all papers may be classified from the stand point of their basic fiber composition into sets of fiber mixtures namely mechanical pulp, soda-sulfate mixture, and rag sulfate 2.**Sizing Material**- improve the quality of paper (texture) such as rosin, casein, gelatin, and starch.. 3.**Loading Material**- add weight to the paper it partially fill the pores between the fibers of the papers such as calcium sulphate and barium sulphate. **Four Test of Paper** 1\. **Preliminary Examination** deals with the appearance of the document as observed the folds and creases, odor, impression caused by transmitted light and presence of discoloration in daylight and under ultra violet light. **Water Marks** - distinctive marks or designs placed in the paper at a time of its manufacture by a roll usually a dandy roll. **Wire Marks,** marks produced on paper by a flexible wire soldered on the surface of the dandy roll that carries the water marks. 2\. **Physical Test Causing No Perceptible Change** *Test applied on the paper without perceptibly changing or altering the original appearance of the document* (measurement of length and width, measurement of thickness, measurement of weight/unit area, color of paper, texture, gloss, microscopic examination and opacity (the quality of paper that does not allow light to pass through in an object. 3\. **Physical Examination Causing a Perceptible Change** *This is done only when sufficient samples are available and if proper authorization from the court is acquired.* (a.) **Bursting strength test or POP test** apparently pressure necessary to burst a hole in a sheet when properly inserted in suitable instrument (b.) **Folding endurance test** it is obtained on an instrument which registers the number of alternate folds the paper will stand before breaking. (c.) **Accelerated aging test** there are some methods of artificially aging document. Soaking in coffee solution, soaking in tea solution, exposure to charcoal, ironing, heating in an oven, exposure to ultraviolet. (d.) **Absorption test** made to determine either the rate of absorption of the paper. 4\. **Chemical Test** determines the fiber composition, loading material, and sizing material used in the paper **INK** - Some of the most important question arises in the analysis of inks are whether the ink is of the same or alike or different in kind from ink on other parts of the same document or in other document, whether the two writings made with the same kind of ink were made with the identical ink, or inks of different qualities or in different condition, whether an ink is also as old as it is supposed to be and, whether documents of different dates or a succession of differently dated book entries shows the natural variation in ink writing or whether the conditions point to one continuous writing at one time under identical condition. **Types of ink** 1.**Gallotannic ink or iron ink** - the most frequently used ink for making entries in the record of book and for business today, it is made up of iron salt and nutgall this ink penetrate into interstices of the fiber and not merely on the surface 2\. **Loll logwood ink** - made up of saturated solution of logwood and very small amount of potassium dichromate, this ink is inexpensive, does not corrode steel pen. 3\. **Negrosine ink or aniline ink** - made up of coal tar product called nigrosine dissolve in water, it easily smudges, affected by moisture may be wash off from the paper with little difficulty. 4.**Carbon ink or Chinese ink or India ink** - the oldest ink material known, made of carbon in form of lampblack it does not penetrate deeply on the paper so that it may be easily washed off 5\. **Colored writing ink** - composed of synthetic aniline dyestuffs dissolved in water, ammonium vanadate is added to render writing more permanent. 6\. **Ball point ink** - made up of light fast dyes soluble in glycol type of solvent as carbitol, glycol or oleic acid.