• Do Now:• get handout and paper bag• Take out HW• Work on the Q’s below:

• Agenda:• Collection of evidence• Types of Evidence

• HW:• Sock prelab• Prep lab notebook

Let the evidence speak for itself.

Presentation developed by T. Trimpe 2006 http://sciencespot.net/

Source: http://www.virtualsciencefair.org/2004/fren4j0/public_html/trace_evidence.htm

"Every Contact Leaves a Trace"

• The value of trace (or contact) forensic evidence was first recognized by Edmund Locard in 1910.

• He was the director of the very first crime laboratory in existence, located in Lyon, France.

The Locard’s Exchange Principle:

"with contact between two items, there will be an exchange."

For example, burglars will leave traces of their presence behind and will also take traces with them. They may leave hairs from their body or fibers from their clothing behind and they may take carpet fibers away with them.

• How does the textbook define physical evidence?•Physical evidence is any object that can establish that a crime has been committed or can link a crime and it's victim or a crime and it's perpetrator.

• Forensic science starts at the crime scene where evidence is recognized and properly preserved.

1. Photography (www.mycrimekit.com)2. Sketches3. Conduct a systematic search for

evidence4. Collect physical evidence5. Maintain the chain of custody6. Obtain standard reference samples7. Submit evidence to the laboratory

• EVERY person who has come into contact with the evidence•handled•examined

• Acts as a “paper trail”• Failure to do so:• lead to questions regarding the authenticity and integrity of the evidence and the examinations

• When evidence is is analyzed there must be a new seal made

• Procedures• Identify the evidence• (is it evidence, could it contain evidence?)

•Decide which type of packaging would be the most appropriate • (plastic pill bottle, manila envelope, paper bag, a

sealed container?)•Record where evidence was found• (living room, northeast corner of park, etc.)

•Label the evidence• (victim’s shirt, hat)

•Date and intial • (you will keep a record of when you collected the

evidence and that you collected)

•Tag the evidence for identification•Seal the evidence• (put tape on it to make sure no one else

has opened/compromised the sample)•Fill out an evidence submission form•Maintain records on chain of custody• Every person that handles the evidence

needs to log it.

• Paint• Glass• Explosives• Ballistics• Dust & Dirt• Impression

evidence• Fracture matches• Wounds

• Questioned documents

• Insects• DNA

Skeletal remains• Body fluids• Hairs & Fibers