Forensic Science Overview: Evidence, Categories, and Analysis Methods

1. Unit 1:Introduction to Forensic Science and Evidence

2. What is forensic science?

3. Forensic Science • Definition: The study and application of science to matters of law.

4. Jobs of Forensic Scientists: • Analyze & examine Evidence • Follow scientific protocols • Provide timely, accurate, and thorough information • Testify in court regarding results of analysis

5. Types of Forensic Scientists: • Anthropologist • Odontologist • Entomologist • Pathologist • Toxicologist • Serologist • Crime Scene Technician

6. Toxicology • Drugs • Latent Fingerprint • Polygraph • Voiceprint Analysis • Cybertechnology • Psychiatry • Accounting • Arson • Evidence Collection • Crime Scene Investigators Crime Lab Units • Physical Science Unit • Glass/Fibers/Soil/Impressions/Markings • Biology Unit • Serology (blood) • DNA Analysis & Blood Splatter • Anthropology (Human Remains) • Pathology (disease) • Odontology (teeth) • Firearms Unit • Ballistics • Document Examination Unit • Forgery

7. Major Crime Laboratories • FBI-Federal Bureau of Investigation • Full Service • DEA-Drug Enforcement Administration • Drug Investigations • ATF-Alcohol Tobacco and Firearms • Firearms/Bombs • U.S. Postal Service • Crimes involving mail • U.S. Fish and Wildlife Service • Environmental Services

8. What is evidence? • What do you think the definition of evidence is? • What types of evidence can you think of?

9. What is evidence? • Definition: anything that tends to establish or disprove a fact

10. Federal Rules of Evidence In order for evidence to be admissible, it must be: • Probative—actually prove something • The more directly linked to a suspect the more probative it is • Example: Fingerprints are more probative than fibers or glass found at the scene • Material—address an issue that is relevant to the particular crime

11. 1923 Frye v. United States Scientific evidence is allowed into the courtroom if it is generally accepted by the relevant scientific community. The Frye standard does not offer any guidance on reliability. The evidence is presented in the trial and the jury decides if it can be used. Admissibility of Evidence

12. Categories of Evidence • Direct Evidence • Proves a direct fact • Examples: • Eyewitness Testimony • Surveillance Video • Circumstantial Evidence (aka Indirect Evidence) • Implies a fact (but does not prove it directly) • Most types of evidence fall under this category • Physical and Biological Evidence • Examples: • Hair/Blood/Fingerprints/Documents/Glass/Impressions etc.

13. Classification of Evidence by Nature • Biological—blood, semen, saliva, sweat, tears, hair, bone, tissues, urine, feces, animal material, insects, bacterial, fungal, botanical • Chemical—fibers, glass, soil, gunpowder, metal, mineral, narcotics, drugs, paper, ink, cosmetics, paint, plastic, lubricants, fertilizer • Physical—fingerprints, footprints, shoe prints, handwriting, firearms, tire marks, tool marks, typewriting • Miscellaneous—laundry marks, voice analysis, polygraph, photography, stress evaluation, psycholinguistic analysis, vehicle identification

14. Evidence Characteristics Fibers Shoe Prints • Class—common to a group of objects or persons • Individual—can be identified with a particular person or a single source Shoe Prints Fingerprints Blood DNA Typing

15. Class or Individual? • These fibers are class evidence; there is no way to determine if they came from this garment. • The large piece of glass fits exactly to the bottle; it is individual evidence.

16. Eyewitness Testimony(Testimonial Evidence) Statement under oath by a competent witness

17. Expert Testimony • Testimony made by a qualified person about a scientific, technical, or professional issue. • Effectiveness Depends On: • Their experience level • Their education • How well they communicate • Cannot be hearsay • Secondhand information • I heard that he…

18. How to be a Good Observer Observe systematically— • Start at one part of a crime scene and run your eyes slowly over every space. • Slowly look at every part of a piece of evidence. • Do not assume that later on you will be able to remember everything.

19. How to be a Good Observer Turn off filters— • Do not pay attention to only what you think is important. • On a crime scene you will not know what will turn out to be important. • Make a conscious effort to pay attention to all the details in your surroundings.

20. How to be a Good Observer Interpret Data Later— • Do look for patterns and make connections. • But the more information obtained, the better will be the interpretations. • Remember that eyewitness accounts and your own thinking can include prejudices.

21. How to be a Good Observer Documentation— • It is important to write down and photograph as much information as possible. • Keep in mind that memory is faulty. • Remember that our brains tend to automatically fill in gaps in our perceptions.

22. Are You a Good Eyewitness?? • You will have 30 seconds to look at a picture and study it. • When time up, I will ask you several questions about the picture. • Answer the questions on the handout • When we are done we will find out who would make a good eyewitness!!!

23. READY?

24. PICTURE 1

25. Questions • At what location was the photograph taken? • How many cars are pictured? • What color are the cars? •  What types of offices are located in the building? •  How many small trees are in the picture? • The photograph was taken in New York State during which season? • How many people are in the photograph?

26. READY?

27. PICTURE 2

28. Questions • What is pictured in Photograph 2? • Describe the shape of the object pictured. • What are the colors of the object? • What color edged the top of the object? • Upon what is the object displayed? • Describe or sketch the design on the object. • What is the approximate size of the object?

29. READY?

30. PICTURE 3

31. Questions • How many people are in Photograph 3? • What is the sex of the person in the picture? • What is the approximate age of the person in the photograph? • What color is the person’s hair? • Does the person have long hair or short hair? • Does the person have any distinguishing features? Glasses? • Can you describe the person’s clothing? • Can you describe where the picture was taken? • Based on evidence in the photograph, can you form a hypothesis about the person’s occupation? • Is it possible to identify the interests of the person based on evidence in the room?

32. Discussion Questions 1. Did everyone answer all of the questions correctly? 2. Did everyone have the same answers? If not, why? 3. Did you do better with practice? 4. Do you think your observations changed when you were distracted? 5. Would your answers have been good enough to testify in court?

33. Problems with Testimonial Evidence

34. Observations by Witnesses Affected By: • Emotional states (stress level) • More stress = Less detail • Prejudice • Ulterior Motives • Interrogation/Questioning Tactics Used • Time

35. The Innocence Project • Barry C. Scheck and Peter J. Neufeld at the Benjamin N. Cardozo School of Law, starting in 1992, use DNA to examine post-conviction cases. • The project has found that up to 87% of the wrongful convictions they discovered were due to faulty eyewitness identifications.

38. Original Composite Sketch of Cotton

39. The Case of Ronald Cotton Part 1

40. The Case of Ronald Cotton Part 2

42. Value of Physical Evidence • Generally more reliable than testimonial • Can prove that a crime has been committed • Can corroborate or refute testimony • Can link a suspect with a victim or with a crime scene • Can establish the identity of persons associated with a crime • Can allow reconstruction of events of a crime

43. Reconstruction Physical Evidence is used to answer questions about: • what took place • how the victim was killed • number of people involved • sequence of events A forensic scientist will compare the questioned or unknown sample with a sample of known origin (control sample).

44. Types of Physical Evidence • Transient Evidence—temporary; easily changed or lost; usually observed by the first officer at the scene • Pattern Evidence—produced by direct contact between a person and an object or between two objects • Conditional Evidence—produced by a specific event or action; important in crime scene reconstruction and in determining the set of circumstances or sequence within a particular event • Transfer Evidence—produced by contact between person(s) or object(s), or between person(s) and person(s) • Associative Evidence—items that may associate a victim or suspect with a scene or each other; ie, personal belongings

45. Examples of Transient Evidence Transient Evidence—temporary; easily changed or lost; usually observed by the first officer at the scene • Odor—putrefaction, perfume, gasoline, urine, burning, explosives, cigarette or cigar smoke • Temperature—surroundings, car hood, coffee, water in a bathtub, cadaver • Imprints and indentations—footprints, teeth marks in perishable foods, tire marks on certain surfaces • Markings

46. Pattern Evidence—most are in the form of imprints, indentations, striations, markings, fractures or deposits. Clothing or article distribution Gun powder residue Material damage Body position Tool marks Modus operandi (how they did it) Examples of Pattern Evidence • Blood spatter • Glass fracture • Fire burn pattern • Furniture position • Projectile trajectory • Tire marks or skid marks

47. Light—headlight, lighting conditions Smoke—color, direction of travel, density, odor Fire—color and direction of the flames, speed of spread, temperature and condition of fire Location—of injuries or wounds, of bloodstains, of the victim’s vehicle, of weapons or cartridge cases, of broken glass Vehicles—doors locked or unlocked, windows opened or closed, radio off or on (station), odometer mileage Body—position, types of wounds; rigor mortis Scene—condition of furniture, doors and windows, any disturbance or signs of a struggle Examples of Conditional Evidence Conditional Evidence—produced by a specific event or action; important in crime scene reconstruction and in determining the set of circumstances or sequence within a particular event

48. Locard’s Principle: the perpetrator of a crime will bring something into the crime scene and leave with something from it, and that both can be used as forensic evidence Hair/Fibers Fingerprints Blood (due to contact---not from wounds) Footprints/Impressions Paint/Chemicals Body Fluids Examples of Transfer Evidence

49. Associative Evidence—items that may associate a victim or suspect with a scene or each other; ie, personal belongings Identification Cards Security Camera Footage Receipts Personal Belongings Jewelry etc… Examples of Associative Evidence

50. COLLECTING AND PACKAGING EVIDENCE • Why do you think it is important to collect and package evidence correctly? • What could happen to evidence if it isn’t handled correctly? • What type of errors do you think investigators typically make?