Forensic Evidence

1. Forensic Evidence Unit 1

2. Fresh bacon? • 3rd century China murder

3. Eureka! – a bit of history Hint! D = M/V • Hiero, king of Syracuse in the third century B.C., gave a jeweler a bar of gold and ordered the jeweler to make it into a crown. When the jeweler delivered the crown to the king, the king measured the mass of the crown and found that the crown had the same mass as the gold he had given the jeweler. Even so, Hiero was suspicious. He believed that the jeweler had cheated him and substituted some less precious metal for the gold. Hiero asked Archimedes, a natural philosopher, to find a way to demonstrate that the crown was not pure gold.

4. Jackie Chiles Einstein What is forensic science? • Forensic Science • Application of science to help resolve matters of • 1) Criminal Law • 2) Civil Law

5. Federal Rules of Evidence These rules govern what evidence is admissible and how it can be used in court. The evidence must be : • probative – it must prove something • material – it must be relevant and significant to the crime *** hearsay is not admissible – it is what others have said being restated by someone…Gossip!!!!

6. Scientific Evidence Two legal decisions have influenced what scientific evidence is allowed in courts • The Frye Standard – (1923) • the scientific evidence must be generally accepted as true by the community as a whole to be acceptable in the court of law. • The Daubert Ruling – (1993) • Scientific evidence is getting to complex so guidelines were offered • The scientific theory must be testable • Other experts must be able to review the theory to be sure it is valid • The rate of error must be given (percentage error) • The technique must follow standards • The court must decide whether the theory has widespread acceptance inside a specific scientific community

7. before fingerprints…

8. How many people are in the video? Describe the main character(s) in the commercial in terms of: Size Age Skin color Height Weight Hair: style, color, length Clothing Hat Glasses Distinguishing features Jewelry Beard or no beard Any physical limitations Describe the other people in the commercial. Describe the setting(s) of the commercial (where it was located). What furniture, if any, was in the commercial? Was it possible to determine the season? What were the people doing in the commercial? Were there any cars in the commercial? If so, describe the: Model Year Color How long was the video? What is the solgan?

9. What does this say…

10. Illusions • http://www.pbs.org/wnet/brain/illusions/index.html • Perceptions are influenced by our past experiences, imagination, and associations • We believe what we see (or think we see) • 12 angry men old man

11. Perceptual Fallacies • Color constancy • Tree and donkey • Size constancy • Ba Mbuti Tribe • Expectation • Phone in the shower • Clarity in vagueness • Clouds • Constructive Memory • Judging • Friend called when your thinking of them

12. 2 Types of Evidence • Testimonial • A statement made under oath, such as an eyewitness testimony • Physical • An object or material that is relevant to a crime (tangible, large or small)

13. Testimonial Evidence • Interesting Facts • Jury’s are heavily influenced by eyewitness accounts • Most known cases of an innocent person going to jail are due to a mistaken eye witness account • Innocence project: 87% of wrongful convictions due to faulty eye witness accounts

14. Reliability of Eye Witness Accounts • Factors that influence reliability • The type of crime it is and how it was seen by the witness Serious crime? Weapon involved? Is the witness physically similar to the suspect? Was it a stressful situation • Characteristics of the witness Adult vs. children? Alcohol, drug involvement? Poor eyesight or hearing? Head injury? • Manner in which the information is retrieved Interviewing techniques used? Open ended questions…not leading questions (ex. ‘did he have any marks on his face that would suggest he had been in a fight..’) • Witness’s prior relationship with the accused Does the witness know the suspect? • Length of time between the offense and the identification How long has it been since the crime?

15. Police Composite • Composite may be developed from the eyewitness testimony by a computer or forensic artist The bottom line in eye witness testimony is… “Perception is reality”

16. Suspect Composite • You and your partner will be responsible for reconstructing the face of a person • You will have aprox. 1 minute to observe the person • Things to focus on: • Overall shape • Shape of the jaw eyes, nose, mouth • Facial hair • Piercing • Facial markings • Width of neck • Protrusion of ears • Forehand lines • Nostrils

17. Methodology of the Forensic Scientist A fundamental principle of every crime scene studied is… Locard’s Principle “Whenever two objects come into contact, there is always transfer of material.” The methods of detection may not be sensitive enough to demonstrate this, or the decay rate may be so rapid that all evidence of transfer had vanished after a given time. Nonetheless, the transfer has taken place.

18. Value of Physical Evidence Physical Evidence - object or material that is relevant to a crime (tangible, large or small) • Generally more reliable than testimonial • remember eyewitness testimonies in 12 angry men • 5th Amendment • Can prove that a crime has been committed • example - gasoline at a scene of an arson • Can corroborate (support) or refute testimony • can test blood stain to prove the suspects claim it is his own not the victims • Can link a suspect with a victim or with a crime scene • a broken piece of glass found on suspect that matches the headlight of a hit and run • Can establish the identity of persons associated with a crime • fingerprints, DNA, handwriting at the crime scene • Can allow reconstruction of events of a crime • what happened, sequence of events • Provide a powerful interrogation tool • police can ask better questions knowing specific information

19. Value of Physical Evidence • Circumstantial Evidence • Implies a fact or event without actually proving it • Examples: a black hair, a size 11 footprint • You hear people classically say “Oh their case is based on purely circumstantial evidence.” Implying it is not good evidence for the case. • Physical evidence is circumstantial evidence • Probability and Statistics determine whether the circumstantial evidence is useful or not

21. Collecting Physical Evidence The main goal of the forensic science team is … to link the victim, suspect, and crime scene with evidence. Victim Crime Scene Evidence The Forensic Team Coroner or Medical Examiner Law enforcement officials Forensic scientists Crime Scene Investigators Lab technicians Suspect

22. Class Evidence vs. Individual Evidence • Class Evidence – common to a group of objects or persons • Small broken glass • Blood type • Individual Evidence – can be identified with a particular person or a single source • High probability of linking two pieces of evidence • Fingerprints – 1 x 1060 Only useful if it is used in connection with other evidence! Fuzzy Line

23. WTHS Theft • Light brown hair • Shirt with majority black • Blue jeans • Dark colored shoes