1 Classification of evidence Evidence may be divided into two large categories 1.Direct evidence-sworn statements that directly establishes a fact 2. Circumstantial evidence-physical evidence that does not directly establish a fact, rather it requires that a judge/jury must make inference from the evidence presented.

2 Introduction to Forensic Science and the Law Why are eyewitness accounts and confession classified as direct evidence, although at times they have proven to be very unreliable? Direct evidence: Eye witness accounts and Confessions

3 Introduction to evidence Impression evidence- patterns should as shoe tracks, tire impressions, tool marks, blood spatter, bite marks, fingerprints etc. form a recognizable pattern that can be compared to known patterns. Trace evidence-small evidentiary items such as hair, fiber, paint chips, glass and soil that could place the suspect at a crime scene or in contact with the victim. ; Circumstantial evidence Physical Evidence/Tangible evidence

4 Introduction to evidence Circumstantial evidence can be divided into three areas: physical, biological and chemical evidence Physical Science evidence: tangible evidence that relies on the use of physical science Examples: shoe and tire impressions, tool marks, glass, ballistics, blood spatter, automobile accidents, structural analysis ; Circumstantial evidence

5 Introduction to evidence Biological evidence: evidence that is derived from once living organism Examples: blood, saliva, semen, hair, corpse, pollen, plants, urine Chemical Evidence-Utilizes chemical test to either extract or examine evidence Examples: toxicology, paint analysis, fiber analysis, chromatography, pH, spectroscopy ; Circumstantial evidence

6 Introduction to evidence Botany-examination of plant residue or plant fragments, pollen, seeds and soil Forensic Anthropology-identification of human skeletal remain to determine age, sex, race, injuries, cause and manner of death, and time of death. (duties may also include identify victims of mass disasters or those interred in mass graves ; Circumstantial evidence Biological forensic science services

7 Introduction to evidence Forensic Entomology-Application of the life cycles of insects that feed on corpse to determine approximate time of death. Use of insect habitat to determine if a body had been moved Forensic Odontology (forensic dentistry)-matches dental patterns with previous x-rays, dental casts, or photographs in order to identify an unknown corpse Matches suspects teeth with bite mark on victim or food products left at a crime scene Circumstantial evidence Biological forensic science services

8 Introduction to evidence Forensic Pathologist-performs autopsy to determine manner and cause of death, injuries inflicted, when and how the injuries were inflicted. Compiles his information from police reports, suspects and eyewitness accounts, and medical records Forensic Psychiatry-studies and analyzes the state of mind of perpetrators. Provides information about the sanity of criminal to determine their competence to stand trial, sign documents, or give informed medical consent. ; Circumstantial evidence Biological forensic science services

9 Introduction to evidence Serology- analyzes blood and other body fluids such as semen, and saliva. Blood typing, paternity testing, and DNA profiling are performed by serologist. ; Circumstantial evidence Biological forensic science services

10 Introduction to evidence Document Examination- analyzes questioned documents. Questioned documents include documents whose age or authenticity is in doubt, documents which may have been altered. Document examiners use handwriting analysis to match known samples to questioned documents or signature. Document examiners also examine the physical and chemical properties of paper and ink. Circumstantial evidence Chemical science services

11 Introduction to evidence Toxicology-study of drugs and poison. Duties include: determining if drugs or poison is present both living and deceased. Assess contribution of drugs or alcohol to aberrant behavior or death. Identify confiscated drugs ; Circumstantial evidence Chemical science services

12 Introduction to evidence Fingerprint Examination unit- Perform analysis and matching of an unknown fingerprint, palm and foot sole print. Firearms Examination- often referred to as ballistics. Examines weapons, ammunition, fired bullets, shell casings, and shotgun shells. Firearms experts use microscope and various chemical analyses in an attempt identify the type of weapon and to match any fired bullets or shell casings to a suspect weapon. ; Circumstantial evidence Physical science services

13 Introduction to evidence Structural-deals with structures such as buildings and bridges ; Circumstantial evidence Physical science services

14 Introduction to evidence Evidence collection unit-Also called Crime Scene Investigation Unit (CSIU) functions in collecting and preserving evidence from the crime scene and transporting evidence to the lab Duties of the evidence collection team also includes: lifting latent prints, collecting hair and fibers as well as other articles at evidence located at the crime scene. ; Other Forensic Science Services

15 Introduction to evidence Evidence Storage unit- secure place for storing and preserving evidence. Materials must be kept secure for years, or even decades and the chain of custody must remain unbroken to prevent the evidence from becoming compromised and lose its evidentiary value. Photography unit-records the scene, all evidence and a body (if one is present) with still photos as well as videos which are crucial for crime scene reconstruction and presentation of evidence in a courtroom. ; Other Forensic Science Services

16 Introduction to evidence Match each image to the specific physical evidence unit 1. 2.

17 Introduction to evidence Match each image to the correct physical evidence unit ; Other Forensic Science Services

18 Introduction to evidence Match each image to the correct physical evidence unit ; Other Forensic Science Services

19 Introduction to evidence Match each image to the correct physical evidence unit ; Other Forensic Science Services

20 Introduction to evidence Additional videos for structural unit college-parking-garage-collapse_n_ html ; Other Forensic Science Services

21 Circumstantial evidence 1.Why does blood spatter evidence require the application of physical science and not biological science? 2.Why are items such as glass, paint and soil considered trace evidence although they are not usually very small?

22 Circumstantial evidence Homework Refer to slides 6-15 and classify each type of circumstantial evidence into one of the three branches of forensics. Example FieldMedicalLaboratory Botany Psychiatry

23 Forensic science vs Junk science Recently there has been debate about what constitutes forensic science Many of the physical evidence that was once believed to be foul proof have now been discarded as junk science

24 Forensic science vs Junk science In order for forensic evidence to be considered as grounded in science it must conform to the steps of the scientific method We will view two video resources to identify which commonly used “forensic evidence” have now come under scrutiny.