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Concepts of Forensic Science for Lawyers


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Forensic Science for Lawyers
Concepts of Forensic Chemistry

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Concepts of Forensic Science for Lawyers

  1. 1. Concepts of Forensic Science for Lawyers Prof. Prashant Mehta
  2. 2. What is Forensic Science • A special discipline (also called criminalistics) that is used to discover the facts about what happened during a crime. • It is the study and application of science to matters of law (criminal and civil) “science in the service of law”. • Includes providing timely, accurate, and thorough information to all levels of decision makers in our criminal justice system.
  3. 3. • A criminalist examines physical evidence for legal purposes • Criminologists study the crime scene for motive, traits, and behavior as to help interpret the evidence. – They learn to think like criminals Criminalists vs Criminologists
  4. 4. What happens at a crime scene? • The first responding officer must secure and protect the integrity of the crime scene. This is a very important task! Sometimes crimes cannot be solved and criminals are set free because the crime scene was not properly processed. – Gather information – Search for evidence – Document evidence – Collect evidence – Preserve evidence so it remains exactly as it is found at the scene – Conduct field tests – Reconstruct the sequence of events
  5. 5. The primary crime scene is the location where the crime was committed such as a homicide or a robbery. A secondary crime scene could be the location where a murder victim was buried, the victim’s home where evidence of the assailant is found, or a suspect’s home where fibers from the victim’s clothing or hair were found. In order for a location to become a crime scene, there must be evidence found at that site. Primary vs. Secondary Crime Scenes:
  6. 6. • Locard's Exchange Principle states that with contact between two items, there will always be an exchange. This is the basis of trace evidence collection at a crime scene. “Every contact leaves a trace”
  7. 7. Chain of Custody • The collection, labeling, and testing of evidence. There must be a documented trail of exactly who has handled the evidence from crime scene to court. If the chain of custody is broken because of improper handling or labeling of evidence, then the evidence may not be admissible in court.
  8. 8. Kendall/Hunt Publishing Company 8 Forensic Area Collect evidence (non-bodily) Interrogate witnesses Arrest criminals Investigate crime scene CRIMINALISTICS (Forensic Laboratory Experts) LAW ENFORCEMENT (Homicide detective, police, FBI, profilers, others) MEDICAL EXAMINER Forensic Chemist / Toxicologist Questioned Document Examiner Trace Evidence Specialist Serologist / DNAAnalyst Firearms and Toolmarks Examiner Latent Fingerprint Examiner Forensic Pathologist Forensic Entomologist Deputy Medical Investigators Forensic Anthropologist Photos, sketches, notes Bloodspatter Analyst
  9. 9. • Applies the principles and techniques of the physical and natural sciences to the analysis of the many types of evidence that may be recovered during a criminal investigation • May also provide expert court testimony - Known as an expert witness - Individual whom the court determines possesses knowledge relevant to the trial. Forensic Scientists
  10. 10. Developments in Forensic Science • 700s AD - Chinese used fingerprints to establish identity of documents and clay sculptures • ~1000 - Roman courts determined that bloody palm prints were used to frame a man in his brother’s murder • 1149 - King Richard of England introduced the idea of the coroner to investigate questionable death • 1200s - A murder in China is solved when flies were attracted to invisible blood residue on a sword of a man in the community. • 1776 - Paul Revere identified the body of General Joseph Warren based on the false teeth he had made for him
  11. 11. Developments in Forensic Science • 1784 - John Toms convicted of murder on basis of torn edge of wad of paper in pistol matching a piece of paper in his pocket • 1879 - Alphonse Bertillion developed a system to identify people using particular body measurements • 1896 - Edward Henry developed the first classification system for fingerprint identification • 1900 - Karl Landsteiner identified human blood groups • 1904 - Edmond Locard formulated his famous principle, “Every contact leaves a trace” • 1984 - Jeffrey’s developed and used the first DNA tests to be applied to a criminal case
  12. 12. People of Historical Significance • Mathieu Orfila- father of forensic toxicology • Alphonse Bertillion- devised first scientific system of personal identification • Francis Galton- conducted first definitive study of fingerprints and their classification • Leone Lattes- developed a procedure to determine blood type from dried bloodstains • Calvin Goddard- used a comparison microscope to determine if a particular gun fired a bullet
  13. 13. People of Historical Significance • Albert Osborn- developed the fundamental principles of document examination • Walter McCrone- utilized microscopy to examine evidence • Hans Gross- wrote treatise on criminal investigation • Edmond Locard- considered the father of criminalistics; responsible for Locard’s exchange principle – States that when a criminal comes in contact with an object or a person, a cross transfer of evidence occurs
  14. 14. Disciplines in Forensics • Anthropology – examine bones to identify remains and determine other information such as age, race, and gender • Art – identify missing children, victims, or suspects through reconstructive techniques based on age progressions, composite imagery and knowledge of human anatomy. • Crime Scene Investigation – gathering information at a crime scene, collect and preserve evidence • Criminalistics – collect, identify, and analyze physical evidence from a crime scene
  15. 15. Disciplines in Forensics • Engineering – determine material or structural failures and reconstruct events such as accidents or collapse of buildings • Entomology – study insects found on a decomposing body to determine time of death • Jurisprudence – study philosophy of law. • Medicine (Pathology) – study injuries and disease to determine cause and manner of death through an autopsy • Odontology – dentists that identify human remains by matching dental records, and identify bite marks
  16. 16. Disciplines in Forensics • Psychology & Psychiatry – study human or criminal psychology and behavior, and profile criminals and victims • Toxicology – identify and analyze poisons, drugs, and chemicals and study their effects.
  17. 17. Forensic Techniques DNA Analysis Use molecular biology to extract and analyze DNA from blood, semen, bones, body tissue, hair roots, saliva, fecal matter, and any other material
  18. 18. Forensic Techniques Firearms Examination / Unit Analyze firearms, discharged bullets, cartridge cases, shotgun shells, unusual or homemade weapons, and ammunition components. They determine what kind of weapon fired a bullet, match bullets to specific weapons, and determine the trajectory and distance of a shot.
  19. 19. Forensic Techniques Forensic Drug Analysis Analytical chemistry is used to identify the presence and quantity of controlled substances. A drug chemist analyzes unknown powders, liquids, plants, pill, capsules, and other forms of drug
  20. 20. Forensic Serology - Identify blood and other body fluids
  21. 21. Impression evidence Study various types of markings on evidence, such as footwear impressions, tire impressions, and footprints
  22. 22. Latent Fingerprints latent fingerprints are invisible to the human eye. Fingerprints are detected, developed, and processed in order to compare them to known fingerprints for identification
  23. 23. Questioned Document Examination scientific examination of handwriting, typewriting, printing, photocopying, or other mechanical production of written material. Identify ink, paper, or other document components for authenticity, forgery, or alteration
  24. 24. Trace Evidence examine hair, fibers, glass, soil, plants, minerals, and many other different types of materials. Substances are studied under a microscope and chemical techniques can be used to identify and individualize evidence even when found in very small quantities
  25. 25. Voice Analysis ties unknown voices in recorded messages to particular speakers based on speech patterns that are unique to every individual
  26. 26. Photographic Unit • Applies specialized photographic techniques for recording and examining physical evidence
  27. 27. All About Evidence
  28. 28. • Is any item or information gathered at the scene of a crime, or at related locations which tends to disapprove or establish something. • Any tangible material that can be used to prove the facts of a matter in a court of law. • Expert witness: someone who testifies in court as a qualified expert in a particular subject area  It can be divided into two general goods: • Testimonial Evidence • Physical Evidence Evidence
  29. 29. Physical Evidence • Tangible tend to prove or disapprove a fact • Real evidence • Refers to any item that would be present at the crime scene on the victims out found in a suspects possession. • more reliable than testimonial evidence • Can be any material or object in any shape, size, form.
  30. 30. Physical Evidence • Types of Physical Evidence: • Trace Evidence • Transient Evidence • Conditional Evidence • Indirect Evidence • Individual Evidence • Class Evidence
  31. 31. Trace Evidence  refers to physical evidence that is found in small but measurable amounts. (For example: hair, fibers, skin cells, DNA, blood, etc.)
  32. 32. Transient Evidence  temporary evidence can be easily changed or lost. Recorded at the time by usually the first office at the scene. (For example: odors, temperature, imprints, etc)
  33. 33. Conditional Evidence  produced by a specific action or event at the scene. (For example: lights, doors, windows, position of furniture, etc)
  34. 34. Indirect Evidence  does not prove or disprove a fact in question. (For example driving under the influence) +
  35. 35. Individual Evidence  can be related to a single source. (For example fingerprints. Handwritings, etc)
  36. 36. Class Evidence  Can be associated with a group of items that share properties or characteristics. (For example: blue jeans)
  37. 37. Arson Evidence
  38. 38. Physical Evidence
  39. 39. Chemistry The study of composition, structure, properties, and reactions of a substance which help us identify a suspect. Identify and analyze toxic substances, fire accelerants, gunpowder residue, explosives and other chemical substances.
  40. 40. Biology The study of the investigation of living matter, or once living matter, in reference to its origin, behaviour, and classification. Applies the knowledge of biological sciences in order to investigate blood samples, body fluids, hair, and fiber samples.
  41. 41. Physics The study that comprises of all investigations that deal with motion, force, and dynamics. Incorporates the principles of chemistry, physics, and geology to identify and compare physical evidence.
  42. 42. Other Crime Lab Services • Toxicology Unit- examines body fluids and organs for the presence of drugs and poisons • Latent Fingerprint Unit- processes and examines evidence for latent fingerprints • Polygraph Unit- conducts polygraph or lie detector tests • Voiceprint Analysis Unit- attempts to tie a recorded voice to a particular suspect • Evidence Collection Unit- dispatches specially trained personnel to the crime scene to collect and preserve physical evidence
  43. 43. Other Forensic Science Services • Forensic Pathology- concentrate closely on the understanding of types and causation of injuries and causes of sudden and unnatural death – Deals with the different stages of death • Rigor mortis- stiffening of the body (occurs within first 24 hours) • Livor mortis- settling of blood closest to the ground (occurs up to 12 hours) • Algor mortis- results in loss of heat
  44. 44. Other Forensic Science Services • Forensic Anthropology-concentrates on the identification of deceased individuals whose remains are decomposed, burned, mutilated or otherwise unrecognizable • Forensic Entomology- is the study of insects and their relation to a criminal investigation, commonly used to establish the time of death • Forensic Psychiatry- work with courts in evaluating an individual's competency to stand trial, defenses based on mental diseases or defects (e.g., the "insanity" defense), and sentencing recommendations
  45. 45. Other Forensic Science Services • Forensic Odontology- evaluates teeth to determine the identification of the deceased • Forensic Engineering- investigation of materials, products, structures or components that fail or do not operate/function as intended, causing personal injury for example • Cyber technology- involves the examination of digital evidence
  46. 46. Listening Attention Patience Questions