Legal Systems pt. 2 Forensic Science

Objectives 1.Compare and contrast the various types and the value of direct and indirect evidence. (DOK 4) 2.Compare and contrast class and individual evidence. (DOK 4) 3.Recognize examples of class and individual evidence and evaluate the usefulness of various examples of evidence. (DOK 4) 4.Understand and explain the impact of the Frye and Daubert Supreme Court case decisions on the collection and presentation of evidence. (DOK 2, 4) 5.Explain the role of the expert witness, and apply the appropriate evaluation standards to the selection of appropriate witnesses. (DOK 2, 3) 6.Explain the importance of reference samples when collecting comparison-type evidence. (DOK 2) 7.Describe the requirements for the proper packaging of evidence to prevent cross- contamination. (DOK 2) 8.Describe the requirements for maintaining a “chain of custody” and explain the importance of maintaining an unbroken chain. (DOK 1, 2, 4) 9.Evaluate the collection of evidence in case studies to determine if the evidence was collected legally and appropriately. (DOK 6) 10.Suggest procedures to improve the process of legal evidence collection. (DOK 5) 2

The Evidence in Court How evidence is received in a court of law is extremely important to a crime scene professional How evidence is received in a court of law is extremely important to a crime scene professional the importance of proper evidence collection and handling Because of the Constitution’s view of “innocent until proven guilty” and the rights of the accused, it is crucial that those in law enforcement understand the types of evidence, how it is perceived in court, how to testify to its significance, and the importance of proper evidence collection and handling 3

Power of the Evidence in Court Probative Value Probative Value Higher value if the evidence can prove something in court The lower the probability of an event, the higher the probative value Probability Probability – the frequency of the occurrence of an event Defines the odds that a certain event will occur (or the matching of a certain pieces of evidence) Normally found by multiplying the odds 4

Question: Why does something that has a low probability of occurring have a high probative value? 5

Types of Evidence in Court Direct Evidence Direct Evidence – evidence that establishes a fact Eyewitness testimony or victim’s testimony Confessions Audio or visual recording of the act or crime 6

Types of Evidence in Court Indirect Evidence Indirect Evidence Circumstantial evidence Requires that a judge and/or jury make inferences about what occurred at the scene of a crime Physical evidence is nearly always circumstantial, so evidence analyzed forensically is mostly indirect evidence Physical evidence is nearly always circumstantial, so evidence analyzed forensically is mostly indirect evidence Inference example: fingerprints or hairs found at the scene are consistent with that of a perpetrator; jurors may infer that the print or hair belongs to the defendant, linking him to the scene. 7

Influence of Direct vs. Indirect Evidence Indirect circumstantial evidence is more objective, while direct evidence is subjective Indirect circumstantial evidence is more objective, while direct evidence is subjective In general, direct evidence is not considered to be as reliable as circumstantial evidence – Eyewitnesses can be mistaken when identifying perpetrators or remembering certain events – Flawed questioning techniques can lead to false testimony and confessions – The age of the eyewitness and the passing of time since the event can also lead to faulty testimony 8 “Direct” does NOT mean better!

Influence of Direct vs. Indirect Evidence (continued) Court research comparing the impact of the type of evidence shows mixed results: Court research comparing the impact of the type of evidence shows mixed results: Some research says direct (eyewitness) evidence has a stronger impact on the jury At other times, physical evidence was considered more valid by jurors both Some studies suggest that having both types of evidence is no more compelling than having strong evidence of only one type 9

Influence of Direct vs. Indirect Evidence (continued) The forensic scientist should The forensic scientist should Always be aware of the persuasive nature of eyewitness testimony In no way allow that to interfere with the scientific method when analyzing physical evidence or developing a hypothesis when investigating a crime The direct evidence of a police officer’s testimony (concerning the source of evidence, documentation, and chain of custody) confirms and strengthens the probative value of physical evidence Be unbiased! Be unbiased! 10

Categories of Physical Evidence Individual Evidence Individual Evidence – can be linked to a unique, specific source (individual) with a very high degree of probability Examples Matching ridge characteristics of fingerprints Matching striations of two different bullets from the same gun The irregular edges of a broken object (paper, glass, etc.) that fit together like a jigsaw puzzle (this type of evidence is not found very often) DNA 11

Categories of Physical Evidence (continued) Class Evidence Class Evidence – evidence that can only be associated with a group and never a single source Examples: a paint chip, blood of a certain ABO type The way to increase the probative value of class evidence is to find as many different types of class evidence as possible to link the suspect to the crime Multiple pieces of class evidence can be convincing Multiple pieces of class evidence can be convincing 12

Individual vs. Class Evidence Activity

Evidence Admissibility In a Court of Law Not only will the court compare the Bill of Rights to how evidence was collected, but there are court precedents that determine the admissibility of scientific results and how those results are explained in court Frye v. United States, 1923 – The Frye Standard: generally accepted Frye v. United States, 1923 – The Frye Standard: the questioned scientific procedure or principles must be “generally accepted” by a majority of the scientific community 14

Evidence Admissibility In a Court of Law (continued) Daubert v. Merrell Dow Pharmaceuticals, 1993 Daubert v. Merrell Dow Pharmaceuticals, 1993 Verdict replaced the Frye Standard Trial judges are responsible as “gatekeepers” for the admissibility and validity of scientific evidence presented in their courts, as well as all expert testimony. 15

Daubert vs. Dow Pharmaceuticals (Continued) Admissibility is determined by: Whether the theory or technique can be tested Whether the science has been offered for peer review Whether the rate of error is acceptable Whether the method at issue is widely accepted in the scientific community. Whether the opinion is relevant to the issue/ 16

Federal Rules of Evidence – Expert Testimony Expert Testimony – hearsay from a witness is normally not allowed in court, except in the case of an expert witness Expert Testimony – hearsay from a witness is normally not allowed in court, except in the case of an expert witness Expert Witness – a witness “qualified as an expert by knowledge, skill, experience, training, or education” (Deslich, 2006) may offer expert testimony on a scientific matter if – The testimony is based upon sufficient facts – The testimony is the product of reliable principles and methods – The witness has applied the principles and methods reliably to the facts of the case 17

Question: What is the difference between a regular witness and an expert witness? Why are expert witnesses allowed to give their opinion on the stand? 18

Court Significance of Procedures in Evidence Collection and Analysis Every step of the process for collecting, handling, analyzing, transporting, and storing evidence is carefully examined in a court of law. Every step of the process for collecting, handling, analyzing, transporting, and storing evidence is carefully examined in a court of law. There are guidelines that must be followed for the collection of evidence, and for the results to be admissible (useable) in court. There are guidelines that must be followed for the collection of evidence, and for the results to be admissible (useable) in court. – A systemic search for all evidence must be conducted – All evidence must be collected, including large items and trace evidence that must be vacuumed – Must maintain Chain of Custody 19

Comparison-Type Evidence Comparison-type evidence (evidence that can be compared to known samples) should be collected whenever possible Comparison-type evidence (evidence that can be compared to known samples) should be collected whenever possible Reference Samples – samples of known materials should be collected. This is comparison-type evidence. Used for comparison, elimination, and matching to those unknown specimens collected at the crime scene Examples: Paint chip from a hit-and-run suspect Blood and hair samples from the victim, suspects, all family members (and pets), and crime scene investigators 20

Packaging of Evidence Proper packaging and separation of evidence is crucial Proper packaging and separation of evidence is crucial – Cross-contamination (or contact) with other persons or evidence is to be avoided at all costs – Proper tools for collection and storage should always be used (envelopes, vials, bags, etc.) – Never package any two pieces of evidence together – Decontamination of personnel between crime scenes or between suspects is important 21

Chain of Custody Chain of Custody – the witnessed, written record of all individuals who had the evidence in their possession from the crime scene to the courtroom; includes when, where, and for what purpose this transfer of evidence occurred Identify the item of evidence itself, the location, time, and name of person collecting/recording Evidence container should be marked, showing the collector’s initials, the location of evidence, and the date it was received by the collector. 22

Chain of Custody (continued) – Any samples of the evidence taken for testing or any changes in the evidence should be documented immediately – Every individual who possesses the evidence must maintain a written record of its acquisition/disposition and may be called to testify in court; – this includes individuals from the collection, to delivery, to the laboratory analysis, and then into the courtroom with the prosecuting attorney 23

Court Significance of Procedures in Evidence Collection and Analysis (continued) Chain of Custody (continued) Chain of Custody (continued) – To avoid confusion, the number of individuals involved in the chain of custody, should be kept to a minimum – The chain of custody record is often kept as a form on the container or envelope of the evidence – Failure to prove the evidence’s chain of custody may lead to serious questions regarding the authenticity and integrity of the evidence 24

Question: Describe the requirements of maintaining a “chain of custody”, and explain the importance of maintaining an unbroken chain of custody for all evidence. 25

Using Physical Evidence As the number of different objects linking an individual to a crime scene increases, so does the likelihood of that individual’s involvement with the crime. Just as important, a person may be exonerated or excluded from suspicion if physical evidence collected at a crime scene is found to be different from standard/reference samples collected from that subject.

Resources Saferstein, Richard. Forensic Science: An Introduction. New Jersey: Pearson Prentice Hall, Bertino, Anthony J. Forensic Science: Fundamentals & Investigations. Mason, OH: South-Western Cengage Learning, Deslich, Barbara; Funkhouse, John. Forensic Science for High School Dubuque, Iowa: Kendall/Hunt Publishing Company, "Simpson Case Has Errors, Coroner Says." New York Times 21 July 1994, A19 sec. New York Times. New York Times Company. Web. 31 July says.html says.html Jones, Thomas. “Analysis of the O.J. Simpson Murder Trial.” TruTV. July 31, tml tml Linder, Douglas. “Famous American Trials: The O.J. Simpson Trial.” University of Missouri-Kansas City School of Law. 31 July

Resources (continued) “The State of California vs. Orenthal James Simpson” [ transcript of testimony of William Bodziak]. 19 June University of Missouri-Kansas City School of Law. 31 July “The State of California vs. Orenthal James Simpson” [transcript of testimony of Henry Lee]. 19 June University of Missouri-Kansas City School of Law. 31 July Thompson, William. “Proving the Case: The Science of DNA Evidence: DNA Evidence in the OJ Simpson Trial.” 30 December Ramapo College of New Jersey. 31 July 2009, Evidencehttp://phobos.ramapo.edu/~jweiss/laws131/unit3/simpson.htm Forensic-Techniques Forensic-Techniques