Tuesday 11/13/12 AIM: How does physical evidence collected at a crime scene help to solve the case? DO NOW: 1- Define Physical evidence 2-List at least 5 types of physical evidence found at a crime scene. Homework: Take home exam Chapter 2

Physical evidence Any solid or tangible piece of evidence that is collected at a crime scene and: –Tells us that a crime has been committed – connects a crime to a suspect and/or victim

Handout. Thumb tips off cops Read to yourself and answer questions on the back.

Physical Evidence “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… only its interpretation can err.” - Paul L. Kirk, 1974

1. Blood, semen, and saliva. These substances are subjected to serological and biochemical analysis for determination of identity and possible origin.

Semen: water, sugar, sperm

Wednesday11/14/12 AIM: What are the different types of physical evidence collected from a crime scene? DO NOW: take out a # 2 pencil and your take home test Fill in your scantron HOMEWORK: textbook Read pages choose any 5 types of physical evidence to list and describe

Saliva Water, enzymes, epithelial cells Epithelial cells: source of DNA

2. Documents. Any handwriting and typewriting examined for authenticity or source. 3. Drugs. Any substances seized in violation of laws regulating the sale, manufacture, distribution, and use of drugs.

4. Explosives. Any device containing an explosive charge, as well as all objects removed from the scene of an explosion that are suspected to contain the residues of an explosive.

5. Fingerprints. All prints of this nature, latent and visible.

6. Fibers. Any natural or synthetic fiber whose transfer may be useful in establishing a relationship between objects and/or persons.

7. Firearms and ammunition. Any firearm, as well as discharged or intact ammunition, suspected of being involved in a criminal offense.

Period 3 Friday 11/16/12 Aim: How can we distinguish individual and class characteristics? Do Now:What is the source of DNA in each of the following: Blood, semen, saliva HOMEWORK: Textbook read pages Answer questions 1-5 pages 74-75

Textbook read pages answer questions 1-3 on page 46

Physical Evidence Forensic scientist: determine the identity and origin of physical evidence Physical properties: color, density,solubility,refractive index –EASILY MEASURED Chemical properties: observed when there is a reaction with another chemical –Bubble formation( liquid to gas phase change) –pH (percent hydrogen) –Color change –Precipitate formation

Case Study: Coral Eugene Watts Texas and Michigan Burglary and intent to murder 1982 conviction Testimonial evidence: Watts confessed to killing 13 woman but he was tried for 1 Lack of physical evidence He stated he was responsible for 20 other murders Modus Operandi was different in each murder (unlikely for a serial killer)

Coral Watts continued Final conviction was based on the testimonial evidence of Joseph Foy in the murder of Helen Dutcher Michigan Eyewitness account 25 years prior which was the only evidence admitted At his trial he confessed to 80 other murders

Individual vs class evidence Individual Evidence: can be linked to one single person Class evidence: linked to a group of people

How can we individualize the following pieces of evidence? 1- A medium, Gap, white T-shirt –Gets torn at a crime scene

8. Glass. Fragments may be transferred to a person or object during a crime. 9. Hair. Collected hairs can link a person to a crime. 10. Impressions. This category includes tire markings, shoe prints, bite marks in skin or food

Trace evidence: Any small item of evidence – hair, fiber, paint, glass, or soil, for example – that places the suspect at the scene of the crime or in direct contact with the victim is considered trace evidence.

Pd 5 Friday 11/16/12 AIM: How can we analyze physical evidence extracted from a crime scene? DO NOW: Classify each of the following as individual or class evidence. Explain how you would individualize each piece of class evidence. 1- A bloody knife found in the backyard of a murder suspect 2- A tire impression from a 1993 honda Civic 3- A cigarette butt found at a crime scene 4- A paint chip with five layers of paint

Product Rule Used in attempt to individualize class evidence Multiply the frequency of independent genetic markers to obtain the overall frequency of occurrence Help create an individual genetic profile

Collecting Evidence At A Crime Scene (At The Scene Of A Crime)

Assessment What type of physical evidence would you collect from the crime scene to your right? For each piece of evidence explain if it is individual or class

AIM: how can we collect physical evidence from a crime scene? DO NOW: 1906 NYPD fingerprinting handout. Homework: Textbook read pages answer questions 1-13 pgs

AIM: What are some types of physical evidence collected at a crime scene? DO NOW: analysis of paint chips and hair fibers handout Homework; Textbook read pages List and describe the significance of physical evidence at a crime scene Textbook read pages If you were a juror and the suspect has blood type A but only blood types AB and O are found at the crime scene, would you convict him/her?