Forensic Chemistry and Toxicology Prelim Coverage 2024-2025 PDF

Prepared by: Joesel B. Villegas, R. Crim. FORENSIC – 3 Forensic Chemistry and Toxicology Prelim Coverage What is a Forensic Chemistry? Forensic Chemistry refers to the...

Prepared by: Joesel B. Villegas, R. Crim. FORENSIC – 3 Forensic Chemistry and Toxicology Prelim Coverage What is a Forensic Chemistry? Forensic Chemistry refers to the branch of chemistry that deals with the application of chemical theories and principles in the solution of legal problems in relation to the administration of justice. This field of study applies science and technology to investigate and establish facts in criminal or civil courts of law. In simple terms, forensic chemistry is the application of chemistry to law. The word “forensic” is derived from the Latin word “forensis”, which means “of the forum”, or speaking the truth in public. The forum, arguably the historical equivalent of modern day courts, is also a place where ancient Romans used to conduct public discussions. What is a Forensic Science? Forensic science is the application of scientific principles to criminal and civil laws, which are enforced by police agencies in a criminal justice system. What is a Forensic Toxicology? Deals with the examination of human internal organs, food samples, water, and gastric contents for the purpose of detecting the presence of poisons substance, its dosage, effect, and treatment. Locard’s Exchange Priciple He is best known for the Locard’s exchange principle, which has been adopted as one of the tenets of forensic science. The principle holds that “every contact leaves a trace,” or “that every contact between two objects results in an exchange of traces between them”. The Stalwarts in the History of Forensic Science Mathieu Joseph Bonaventure Orfila (1787 – 1853) ✓ Considered as the Father of Modern Toxicology. ✓ Established numerous basic principles of modern toxicology and is probably the first person to conduct experiments on the effects of poison. Alphonse Bertillon (1853 – 1914) ✓ Established the first scientific system of personal identification by a series of bodily measurements. Francis Galton (1833 – 1911) ✓ First to study fingerprints and classify them for filing. Leone Lattes (1887 – 1954) ✓ Discovered that blood can be categorized into four groups. Calvin Goddard (1891 – 1955) ✓ Determined the comparison of bullets in guns – Ballistics. Albert S. Osborn (1858 – 1946) ✓ Developed principles of document examination. Walter C. McCrone (1916 – 2002) ✓ Developed advances in microscopic techniques to solve crimes and analyze evidence. Hans Gross (1847 – 1915) ✓ Studied and developed principles of criminal investigation. Edmond Locard (1877 – 1966) ✓ Had a background in medicine and law, and was the first one to use scientific methods for criminal investigation. Importance of Forensic Chemistry Forensic science deals with the application of science to legal matters and crime solving. Chemistry plays an essential role in the interdisciplinary field of forensic science, especially in the crime laboratory wherein the same principles and laws of chemistry are used to examine evidence (Johnll, 2009). Scope of Forensic Chemistry ✓ It includes the chemical side of criminal investigation ✓ It includes the analysis of any material the quality of which may give rise to legal proceeding. ✓ It is not limited to purely chemical questions involved in legal proceedings. ✓ It has invaded other branches of forensic sciences notably legal medicine, ballistics, questioned documents, dactyloscopy, and photography The Role of the Chemist in Scientific Criminal Investigation A chemist may be called upon to perform various tasks. Some of his jobs were enumerated below. ✓ Aid an investigator whether any article found in the crime scene such as hair, blood and blood stains, documents, etc. belong to the offended party or to the offender; ✓ Give analysis for the purpose of developing investigative leads and establishing aggravating or mitigating circumstances in the commission of a crime; ✓ Establish facts constituting a criminal violation, etc. ✓ Offices. The Crime Laboratory A crime laboratory (or “crime lab” for short) is a scientific laboratory that uses forensic science for the purpose of examining evidence from criminal cases. It refers to a laboratory where highly trained technical personnel render various related services. The PNP Crime Laboratory consist of uniformed and non-uniformed personnel with high level expertise and the ability to provide scientific investigation services through fieldwork, crime scene operations, forensic laboratory services, as well as criminalistics training and research. Allied services includes autopsy, drug test, DNA examinations, examination of questioned documents, fingerprinting services, histopathological examinations, macro-etching examinations, semen determinations, and so on. Requesting parties must submit an official letter of request for the specific service, together with the evidence or specimen and other details about the specimen, suspect, the time and date of confiscation, the nature of the case, and the type of examination requested. In drug specimen, a chain of custody form must be completed and signed by all persons who handled the subject drug specimen. Below is a table showing the jurisdiction of physical evidence according to the examination to be performed. Table show the jurisdiction of physical evidence according to the examination to be performed; Physical Nature, Evidence Branch of Examiner (PNP Crime Lab) ✓ Fingerprints ✓ Fingerprint Division ✓ Firearm Evidence ✓ Firearm Identification Division ✓ Biological Evidence ✓ Biological Evidence ✓ Trace Evidence ✓ Physical Identification Division ✓ Document Evidence ✓ Questioned Document Division ✓ Physical Matching Evidence ✓ Physical Matching Evidence ✓ Toxicology Evidence ✓ Chemistry Division  ✓ Drug Evidence ✓ Chemistry Division ✓ Macro-Etching for Vehicles ✓ Physical Identification Division The Forensic Chemist A forensic chemist is a professional chemist who analyzes evidence from the crime scene and derives a conclusion based on tests undertaken on such evidence. It is the task of the forensic chemist to identify and characterize the evidence as part of the overall crime solving process. Given that they handle the evidence collected from the crime scene, they are often summoned to explain in a trial court what was found and how they arrived at their conclusions. They can provide technical explanation that can assist in a final judgment as well as analyze the evidence. However, they cannot determine the verdict. Versatility and patience are the oft-cited qualities of the forensic chemist. Characteristic of a Forensic Chemist 1. Be able to spend hours rigorously applying analytical techniques to evidence; 2. Clearly and concisely answers challenges to his findings;and 3. Possess moral integrity. Functions of a Forensic Chemist 1. Conduct qualitative and quantitative examination of dangerous drugs as well as volatile substances. 2. Conduct examination of explosives and/or explosive ingredients. 3. Conduct examination of firearms and paraffin casts to detect the presence of gun powder nitrates or gunpowder residue (GPR) 4. Conduct gunpowder examination of clothing to verify possible gunshot distance 5. Conduct chemico-toxicological examination of human internal organs, gastric contents, blood water, food samples, and other substances. 6. Conduct examination of fake products in case of unfair trade competition. 7. Conduct blood alcohol determination 8. Examined urine and other bodily fluids for the presence of dangerous drugs 9. Conduct research and training related to the cases being examined 10. Deliver lectures on forensic chemistry and toxicology to police and military training centers, investigative units, schools, and universities. 11. Testify to provide expert opinion in court as well as attend court duty as an expert witness 12. Respond to queries of all investigative units and render expert opinion regarding matters related to the application of chemical principles, for the purpose of assisting investigators in developing investigative leads. 13. Conduct field laboratory work and clandestine laboratory investigation Four Stages in the Practice of Forensic Chemistry Stage 1: Collection and Reception of the Specimen. Collection refers to the proper collection, handling, and packaging of specimen before an analysis can be started. Reception refers to the process of receiving the specimen by entering the specimen condition on the log book. Stage 2: Actual Examination The conduct of various examination procedures for different specimens submitted as requested by the requesting party. Step 3: Reporting Writing of the Result. This step involves the drafting of the positive or negative result (e.g., presence of a drug).  Step 4: Court Appearance. This is the final stage, wherein the chemist must explain to the court the findings of the examination conducted on the specimen submitted. The Forensic Chemist as an Expert Witness in Court A forensic chemist can be called in as an expert witness in a court of law by virtue of the following qualifications: ✓ Education ✓ Training ✓ Experience A qualified expert may testify “in the form of an opinion or otherwise” so long as the following criteria are met: ✓ The testimony is based on sufficient facts or data. ✓ The testimony is the product of the application of reliable principles and methods. ✓ The witness has applied the principle and methods reliably to the facts of the case. Golden Rules in the Practice of Forensic Chemistry As with other disciplines, there are several important rules that must be followed, which include the ones listed below; ✓ Go slowly ✓ Be thorough ✓ Take notes ✓ Consult others ✓ Use imagination ✓ Avoid complicated theories What is Physical Evidence? ✓ Refers to any material object introduce in a trial for the purpose of proving a fact in issue based on its demonstrable physical characteristics. This includes all or part of any conceivable object. ✓ Physical evidence found at a crime scene in small but measurable amounts are called trace evidence. Such evidence include body fluids, DNA, fingerprints, hair and fibers, paints, glass, explosives, ballistics, impression, questioned document. The identification of physical evidence can help determine the truth during the investigation of a crime. Types of Physical Evidence. ✓ Corpus Delicti Evidence – Objects or substance which may be a part of the body of the crime. ✓ Associative Evidence – These are physical evidences which link a suspect to the crime. ✓ Tracing Evidence – These are physical evidences which may assist the investigator in locating the suspect. Physical Evidence can be classified according to the following: ✓ Physical nature – microscopic, solid, liquid, gaseous, etc. ✓ Type of examination to be conducted – drug test, drug analysis, paraffin test, etc.. There are several types of physical evidence that are likely to be found at the scene of a crime, and can be analyzed scientifically; ✓ DNA ✓ Body fluids ✓ Impressions ✓ Weapon ✓ Question documents ✓ Miscellaneous trace evidence Value of Physical Evidence It has already been mentioned that physical evidence is much more reliable than testimonial evidence. ✓ Human Factors ✓ Physical Properties Circumstantial Variability If any type of physical evidence is found and subsequently associated with a suspect where he or she had no right to be, then upon proper identification, the evidence may; ✓ Establish proof beyond reasonable doubt. ✓ Establish probable cause. ✓ Establish a suspect’s presence at the crime scene. If the physical evidence is found for a period during which a suspect may have had legitimate right to be (i.e., innocent access), then the evidence may; ✓ Have no significance. ✓ Provide leads to follow in order to establish the case via other sources. Collection of Physical Evidence The scene of the crime operation (SOCO) team must have several main goals in mind during the process of collecting evidence from a crime scene; reconstruct the crime, identify the person who committed the crime, preserve the evidence for analysis, and collect such evidence in a way that will make them stand up in court. Trace Evidence ✓ Trace evidence constitute the most common type of physical evidence, which an investigators and/or crime scene specialist is likely to encounter. ✓ Trace evidence refers to microscopic materials found at a crime scene, such as hair, blood, glass particles, foot/tire impression, fiber, or paint, to name a few. Note: “It is important to note that evidence containing moisture should not be packaged in plastic or paper containers for a period exceeding two hours.” This is because moisture facilitates the growth of microorganisms, which can destroy or alter the quality of the evidence collected. Guiding Principle in the Collection of Physical Evidence There are several guidelines in the collection of physical evidence. These help ensure that the appropriate protocols are followed, resulting in the generation of useful evidence. ✓ Sufficiency of sample ✓ Standard for comparison ✓ Maintenance of individuality ✓ Labeling and sealing Reasons for the Loss of Prosecutive Value of Evidence ✓ Improper packing of the specimen, ✓ Failure to identify the specimen, ✓ Improper precautions used in transmitting the specimen, ✓ Improper preservation, and ✓ Lack of precaution to prevent tampering of the specimen. What is Chain of Custody? ✓ The chain of custody refers to a written record of all the individuals who maintained unbroken control over certain items of evidence collected from a crime scene. This establishes the proof that the items of evidence collected at the crime scene are the same items being presented in a court of law, hence validating their origin. Proper Tagging, labeling, and Marking of Evidence ✓ Certainly, it is very important to properly tag and label items of evidence. A crime scene investigator or evidence recovery technician must be able to tag/mark items of evidence so that these can be easily identified at a later date. The tagging, labeling, and marking of the evidence ensures the proper identification of the evidence and ensures the credibility of the evidence collected. The Evidence Custodian ✓ An evidence custodian is the person responsible for preserving the chain of custody of each item evidence submitted by the examiner; he or she ensures the security and integrity of such evidence. The evidence custodian is also responsible for receiving inventories, logs, stores, packages, and issue and providing assistance in the release of that adjudicated piece of evidence. Furthermore, the custodian must keep the evidence safe by placing it inside the evidence room. The Evidence Room ✓ An evidence room or property room refers to a secure facility or room, in which evidence related to criminal cases or investigations are stored. The evidence custodian always has direct supervision of this room. The evidence room is often located inside the forensic laboratory itself, and is used to store old evidence. It is also used to stored physical evidence apart from transcripts, recordings, and other supporting information. Sometimes, case files are also stored in the evidence room, depending on the organizational structure of the department. The contents of the evidence room are stored and organized through a database that has references for all the items stored in the room, along with notations indicating their specific locations. DANGEROUS DRUGS What is a Drugs? Is any synthetic or natural substance that is used to produce psychological or physiological effects in humans; it can also play a central role in the daily lives of many people regardless of whether it is used legitimately or illegitimately. The legality and social acceptance of a particular drug often relies on the purpose and duration of its use, its side effects, and the person using it. CLASSIFICATION OF DRUGS Stimulants Drugs that increase the rate of the body’s system, resulting in increased alertness and physical disposition are called stimulants. These includes prescription drugs (e.g., amphetamines, methylphenidate, diet aids) and illicitly produced drugs (e.g., methamphetamine, cocaine, and methcathinone). Stimulants typically come in the form of powder, pills or capsules, rocks, or injectable fluids. Depressants Are the kinds of drugs that induce sleep, prevent seizures, as well as relieve anxiety and muscle spasm. Using depressants can rapidly lead to dependence and tolerance. This means that the users’ need increases consistently so that they can function normally, thus increasing the likelihood of coma or death. Hallucinogens Drugs Are drugs that produce delusions, and hallucinations as well as severe changes in mood and behavior. In fact, users speak of “hearing” and “seeing” sounds. This major classification includes Marijuana, Cannabis, or Indian Hemp. Narcotics Drugs The term “narcotics” comes from the Greek word for “stupor”. The term was originally used to refers to a variety of substances that relieved pain and dulled the senses. Although some people still refer to all drugs as “narcotics”, the term “narcotic” today refers to Opium, Opium Derivatives, and their semi-synthetic substitutes. A more current term for these drugs is “Opioid” and some examples include heroin and some pharmaceutical drugs such as Fentanyl, OxyContin, Codein, Vicodin, Methadone, and Morphine. Designer Drugs This classification pertains to drugs that combine the effects of chemically related but different known psychotropic and narcotic substances. These are designed by clandestine chemists with the aim of manufacturing compounds that produce the “high” of the main drugs and to avoid penalties imposed against those illegally trafficking the controlled substance. Inhalants Drugs Are volatile substance derived from chloroform or ether. These are often inhaled through the nose to experience intoxication. Common household product, such as lighter fluid, glue, paint, and cleaning fluids produce chemical vapors that can be inhaled. Commonly Abused Drugs in the Philippines: ✓ Methamphetamine ✓ Marijuana ✓ Ecstasy Forensic Drug Analysis That is refers to the process of identifying and quantifying specimen of illegal drugs. These forensic drug tests are carried out via screening and confirmation for the purpose of analysis. The results can be used as evidence in a court of law. Forensic drug analysis deals with the identification and quantification of illegal drugs. Forensic drug tests are generally carried out in two steps: screening and confirmation. Once drugs are detected through screening, for example spot test kits (e.g., immunoassays, Marquis test, etc), samples are then collected and sent to laboratories for confirmation tests. Forensic Drug Chemist Is a specialist who conducts chemical analyses of evidence confiscated during criminal investigations, which involve dangerous drugs and clandestine laboratory. Forensic Drug Chemistry involves the analysis of controlled substances in relation to criminal investigations or drug crime trends. Drug evidence may be in the form of plant materials, liquids, or paraphernalia. Drug Chemists analyze new compounds to determine the processes and materials that are used to manufacture them, as well as their effects on the physiology of users.. Qualitative and Quantitative Analysis of Drug Specimen In the analysis of drugs specimens, it is important to know the qualitative and quantitative characteristics of said specimens. The result of a well-executed drug analysis can be used as the basis upon which a prosecutor can file a case against a suspect. In drug parse, knowing the quantity is knowing its degree of purity, while knowing the quality simply means knowing the existence or the presence of dangerous drugs on the specimen. Both qualitative and quantitative analyses use the analytical method of identifying volatile substances and dangerous drugs. Qualitative Quantitative ✓ Knowing the existence or the presence of ✓ Knowing its degree of purity. dangerous drugs on the specimen. Steps in Conducting Qualitative Analysis Physical Test This kind of test is performed by describing the physical properties of a specimen by ocular inspection, weighing, or through a microscopic exam. Chemical (Color) Test In the chemical test, a specific reagent or series of reagents is used for a presumptive test. Color reaction is expected to occur in order to determine the presence of a dangerous drugs. Different reagents are used for different dangerous drugs and examples include Simons Test, Marquis Test, and so on. Confirmatory Test There are three types of confirmatory tests: Thin Layer Chromatography (TLC), Spectrophotometry, and Gas Chromatography Mass Spectrophotometry. Thin Layer Chromatography (TLC) This type of test requires the comparison of Rf (retention in time values) between the specimen in question and the standard. Spectrophotometry (UIV and IR) Ultraviolet spectrophotometry (UIV) offers conclusive proof for the positive identification of drugs because other materials could produce an indistinguishable spectrum. Meanwhile, infrared spectrophotometry (IR) can specifically identify the substance. The IR pattern is unique to each compound and can be considered as being analogous to the “fingerprint” of the compound being examined. Gas Chromatography Mass Spectrophotometry This test is performed by combining gas chromatography and mass spectrophotometry, that is, as the sample emerges from the gas chromatography, it immediately enters the mass spectrometer. Then, the sample is exposed to high-energy electrons, causing the sample to fragment or break a part. The fragmentation pattern serves as a “fingerprint” of a chemical substance. Reporting A complete laboratory report should be able to indicate all the necessary information, which includes the following: ✓ The specimen submitted and its description. ✓ The time and date at which the specimen was received by the authorized personnel. ✓ Data about the suspect/s. ✓ The name of the requesting party. ✓ The findings and conclusion. ✓ The time and date at which the analysis was complete. ✓ The name and signature of the examiner and the approving officer. Testing for the Presence of Dimethoxyamphetamine (DMA) Drug Test via Urine Sample The drug test uses a Marquis Reagent in order to obtain a positive result for users of Amphetamine and Methamphetamine during the screening test. ✓ Single use : 1 – 3 days ✓ Heavy use : 3 – 5 days Hair Testing - This test generally uses the most recent 1.5 inch of hair growth, which provides a detection period of approximately 90 days. Result of the Marquis Test and How to Analyze Them COLOR SUBSTANCE PRESENT No Reaction Does not contain MDMA, MDE, MDA Dark Purple to Black Either MDMA, MDE, MDA, DXM or Opiates are present Dark Grey DXM will emit a small amount of smoke Bright Yellow Either DOM or DOB is present Bright Orange Either speed or methamphetamine is present Metabolism of Drugs Methamphetamine -------- Amphetamine Heroin -------- Morphine Aspirin -------- Salicylic Acid Diazepam -------- Oxazepam Ecstasy -------- Amphetamine Three Factors Considered in Drug Physiology ✓ Absorption ✓ Distribution ✓ Methabolism What is Elimination of Drugs? This refers to the method of eliminating body toxins and other unabsorbed products of metabolism (e.g., via the liver) and excretion (e.g., via the kidney, bile). The urine can also be the main route of excretion. What is Drug Test? It is the process of determining the presence of a drug and its metabolites in the human body through the fluids. Other specimens that can be used in a drug test include the following: ✓ Blood ✓ Fingernails ✓ Hair ✓ Saliva ✓ Sweat ✓ Tissue Validity Test in Urine Samples Performing a validity test on a urine sample helps determines the integrity of the sample. The typical reasons for performing the validity tests are: (1) to analyze unobserved urine collection (2) to determine whether a urine sample that submitted has been tampered. A urine sample is considered invalid when it is improperly documented, diluted, substituted, adulterated and improperly collected, handled. Qualitative Examination of Urine Screening Test The drug test kit (DTK) is an easy, fast and qualitative binding immunoassay method that produces a visual result. This is the type of screening without the need of instrumentation. The method uses a combination of monoclonal and polyclonal antibodies to selectively identify the drugs of abuse and their metabolites. Principle of Drug Test Using DTK This kind of drug test is based on the principle of competitive binding. Drugs that may be present in the urine specimen compete against the drug conjugate for binding the antibody. During the testing, urine specimen migrates upward via capillary action. Confirmatory Test This type of test uses Gas Chromatography Mass Spectrometer (GCMS) as an instrument. Cut Off Values Presumptive Positive - The urine sample has a concentration value that is above the cutoff level. Presumptive Negative - The urine sample has a concentration value that is below the cutoff level. NOTE: A negative result does not indicate the absence of the analyze being examined. Drug Detection Based on Urine Sample Drugs Window of Drug Detection in Initial Screen ng/dl Urine Marijuana 2 days to 3 weeks 50 Methamphetamine 2 to 3 days 500 Forms of Specimen Tampering Dilution - This is done by adding water into the urine sample so that minimum required quantity sample can be achieved. Dilution reduces the concentration of normal constituent. Two types of dilution techniques are: ✓ Internal Dilution (Drinking plenty of water to facilitate dilution or taking diuretics like coffee, beer, and tea). ✓ External Dilution (Through the additional of water to the actual specimen). Substitution - This is done by replacing a urine sample with the urine sample of another person. Adulteration - This is done by adding endogenous substances at a concentration that is not a normal physiological concentration. Parameters for Validity Test Initial Validity Test and Confirmatory Validity Test ✓ Physical characteristics, such as color, odor, etc., can be visually determined. ✓ Volume – same as the physical characteristics. ✓ Temperature – a thermometer can be used (normal urine has a lukewarm temperature) ✓ pH level – can be determined using a pH meter. ✓ Specific gravity – can be determined using a refractometer. ✓ Nitrites – can be measured via the calorimetric method. ✓ Creatinine levels ✓ Oxidizing agents OTHER CHEMICAL EXAMINATION OF DRUGS Tests Drugs Nitric Ferric Marquis Froehde Mecke acid chloride Red- Blue- orange green Purple- Blue to changin color Morphine purple-red violet green g to yellow- orange A green, rapidly Yellow- turning to green, olive Orange No color dark green, change green, color Purplish and finally Codeine finally changin violet turning turning blue g to greenish- in about 3 yellow blue or minutes blue within a short time Violet- purple color Light green develops rapidly immediatel Faint No color Reddish- changing Heroine y, on yellow purple to a darker standing it color greenish- turns blue purplish brown Violet color Dissolves Apomorphine changing apomorphi Dark violet to rose-red ne which is  then blue- green color black or violet if the alkaloid is altered by air. Special Test for Morphine ✓ Iodic Acid test – the chloroform layer turns violet ✓ Prussian Blue Test – blue color ✓ Nitrous Acid Test – a yellow green color develops which turns red upon addition of sodium hydroxide. The color is discharged by acid and restored by alkali. Biologic test – if an aqueous solution of morphine hydrochloride is injected under the skin of the back of a mouse, the back takes on loridoctic curvature. The tail begins to rise in an s-shape curve until it finally lies over the back of the animal so that the tip is over the ears. Special Tests for Codeine ✓ Pellagri’s test – emerald green color; red color when shake with ether. ✓ Furfural Test – purple-red color ✓ Prussian Blue Test – green color ✓ Ferric Chloride Test – blue; red color with the addition of a drop nitric acid ✓ Oxidation Test – deep blue color; blue violet – codeine not pure Special Test for Heroine ✓ Prussian Blue test – blue color ✓ Detection of an acetyl group – acetic acid is formed by the hydrolysis of heroine and in the presence of sulfuric acid, it reacts with ethyl alcohol forming ethyl acetate. Special Tests for Apomorphine ✓ Pellagri’s test – blue green to emerald green; violet color with ether extract ✓ Wangerin’s test – violet to the chloroform; change to pure indigo-blue when added with stannous chloride. ✓ Schmidt’s test – fugitive violet color; chloroform is blue ✓ Feinberg’s test – violet red that changes after long standing to a fine violet. Test for Cocaine There are no color tests for cocaine. Special Test for Cocaine ✓ Potassium Permanganate test – violet crystalline precipitate of cocaine permanganate. ✓ Chromic Acid test – crystalline orange precipitate. ✓ Iodic Acid test – appears in succession and together brown, olive-green, blue and violet shades of color. ✓ Detection of Benzoyl Group – odor of methyl benzoate may be noticed. ✓ Physiological test – produce temporary anesthesia of the tongue. Test for Marijuana ✓ Duquenois Test – Blue color ✓ Beam Test – violet ✓ Bouquet Test – brownish red color; whitish opalescence when added with water