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Forensics

Forensics. Chapter 1: Introduction. Forensic Science: A Definition. Application of science to law Applies the knowledge and technology of science for the definition and enforcement of such laws.

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Forensics

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  1. Forensics Chapter 1: Introduction

  2. Forensic Science: A Definition • Application of science to law • Applies the knowledge and technology of science for the definition and enforcement of such laws. Forensic science is the application of science to those criminal and civil laws that are enforced by police agencies in a criminal justice system.

  3. History and Development 1813 1879 Mathieu Orfila: Father of Forensic toxicology Alphonse Bertillon: developed the science of anthropometry 1929 1892 Calvin Goddard: developed the comparison microscope for bullet comparisons. Francis Galton: first study of fingerprints (Nephew of Darwin)

  4. …more History 1910 1950’s Albert Osborne: Principles of document examination Microscope as a tool for the forensic scientist 1893 1910 Hans Gross: Developed the application of scientific principles to criminal investigations Locard’s Exchange Principle

  5. Locard’s Principle "Wherever he steps, whatever he touches, whatever he leaves, even unconsciously, will serve as a silent witness against him. Not only his fingerprints or his footprints, but his hair, the fibers from his clothes, the glass he breaks, the tool mark he leaves, the paint he scratches, the blood or semen he deposits or collects. All of these and more, bear mute witness against him. This is evidence that does not forget. It is not confused by the excitement of the moment. It is not absent because human witnesses are. It is factual evidence. Physical evidence cannot be wrong, it cannot perjure itself, it cannot be wholly absent. Only human failure to find it, study and understand it, can diminish its value.“

  6. Organization of the Crime Lab • Over 320 public crime labs in the U.S…a tripling of the number since 1966. • Supreme Court decision Miranda v. Arizona (1966) • Increase in drug abuse • Advent of DNA profiling • Most State Governments maintain crime labs plus satellite labs.

  7. Physical Science Unit Biology Unit Firearms Unit Document Examination Unit Photography Unit Toxicology Unit Latent Fingerprint Unit Polygraph Unit Voiceprint Analysis unit Evidence Collection Unit Services of the Crime Lab

  8. Physical Science Unit

  9. Physical Science Unit • Investigators: • Chemists • Physicists • Geologists • Items Identified: • drugs, glass, paint, explosives and soil • Job: • Analytical and chemical analysis

  10. Biology Unit

  11. Biology Unit • Investigators: • Biologists • Biochemists • Identify and Compare: • botanical materials such as wood and plants. • Job: • Identification and DNA profiling of dried blood stains, other body fluids, comparison of hairs and fibers

  12. Firearms Unit

  13. Firearms Unit • Identify and examine: • Firearms • Discharged bullets • Cartridge cases • Shotgun shells • Responsibility: • Examination of garments to detect firearm discharge residue • Determine approximate distance from target when weapon was fired.

  14. Document Analysis Unit

  15. Document Analysis Unit • Identify and Examine: • Handwriting and typewriting to determine authenticity and/or source • Job: • Analysis of paper and ink and indented writings (impressions) • Recreate: • Obliterations, erasures • Burned or charred documents

  16. Photography Unit

  17. Photography Unit • Examine and Record: • Physical evidence at the scene • Specialize in: • Digital imaging, IR, UV, and X ray photography to make invisible information visible to the naked eye • Beyond the Scene: • Preparation of photographic exhibits for courtroom presentation.

  18. Can you find the Relationship?

  19. Toxicology Unit • Investigators: • Chemists • Biologists • Examine: • Body fluids and organs for the presence or absence of drugs and poisons. • Determines Blood alcohol content • Job: • Works with the coroner or medical examiner’s office

  20. Latent Fingerprint Unit

  21. Latent Fingerprint Unit • Process and examine: • Fingerprints to determine possible matches with victims and suspects

  22. Polygraph Unit

  23. Polygraph Unit • Job: • Analyze respiration, perspiration, blood pressure and pulse rate to determine credibility • Used in conjunction with interrogation to determine credibility of suspects and witnesses.

  24. Voiceprint Unit

  25. Voiceprint Unit • Interpret: • Telephone threats • Analyze: • Tape recorded messages • Compare: • Suspect voice recording to evidence to match source

  26. Evidence Collection Unit

  27. Evidence Collection Unit • CSI: • Crime Scene Investigation • Consists of: • trained personnel who are dispatched to the crime scene to collect and preserve physical evidence. • They simply collect the evidence, they do not do every single job as seen on fiction television.

  28. Locard’s Principle Revisited • Attempt the Hypothetical Case with a partner. • Answers: • Victim was inside the car means fibers from its interior have been transferred onto the victim’s clothing. • Blood from the victim has been transferred onto the velour interior. • Fiber, blood, hair, and skin cells may also have been transferred between the criminal and victim. • Tire tracks from the car may have been left in the woods. • This would probably lead to the make of car, since the tires are special. • If the vehicle was located, small driving imperfections in the tread could link it to the crime. • The type of soil at the crime scene may still be on the car’s tires, too. • Interior of suspect’s car could be tested for the fibers, hair, skin cells and blood of the victim.

  29. Functions of the Forensic Scientist • Frye v. United States: 1923 Rejection of Lie Detector (Polygraph) results necessitated guidelines for determining judicial admissibility of scientific examinations. • The Frye Standard: The court must decide if the questioned procedure, technique or principles are “generally accepted” by a meaningful segment of the scientific community.

  30. Daubert v. Merrel • Whether the scientific technique or theory can be tested. • Whether the technique or theory has been subject to peer review and publication. • The technique’s potential for error. • Existence and maintenance of standards controlling the technique’s operation. • Whether the scientific theory or method has attracted widespread acceptance within a relevant scientific community.

  31. Coppolino v. State • M.E. testified that victim died of an overdose of a drug called succinylcholine chloride based on his toxicology report. • Succinylcholine chloride breaks down into succinic acid in the body. • This drug had never before been detected in a human body. • Defense argued that this test was new and absence of corroborative experimental data by other scientists. • The court rejected the defense’s argument on the grounds that although the tests may be new and unique, they are admissible only if they are based on scientifically valid principles and techniques.

  32. Expert Testimony • Must be competent: education degrees, member of applicable societies, published papers or books, etc. • Defense may cross-examine the potential expert witness. • The individual trial judge is the ultimate decision maker regarding expert witnesses.

  33. Training in Recognition, Collection, and Preservation of Evidence • Specially trained evidence collectors: CSI • On 24-hour call to aid criminal investigators in retrieving evidence • Specially equipped with all the proper evidence collection equipment • Unfortunately, some police forces still don’t use them or the police themselves have contaminated the crime scene before the CSI team gets there!

  34. Forensic Pathology • Investigation of sudden, unnatural, unexplained, or violent death. • Medical Examiner vs Coroner = M.D. vs political appointee. • Autopsy: http://www.pathguy.com/autopsy.htm • Causes of death: natural, homicide, suicide, accident, undetermined. • Rigor mortis: starts within the first 24 hours and disappears after 72 hours. Helpful in estimating time of death. See “Algor mortis” • Livor mortis: settling of blood after the heart stops. Skin appears dark blue. Used to determine position of body at time of death.

  35. Other Areas involving Forensics • Anthropology: Examination of human skeletal remains • Entomology: insect life span can be used to determine the time of death. • Psychiatry: competency of suspect; serial killed profiles • Odontology: body identification based on dental records; evidence using bite marks left on victims • Engineering: accident reconstruction to determine causes

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