Name ____________________________________ Period__________ Date______________

Trace Evidence

Directions: Open this document on BandwidthOregon.com to access the websites.

Use the websites on the Trace Evidence and MoreForensic Science Links (page 2) of the Kid Zone at: http://sciencespot.net/Pages/kdzforsci2.html to complete this worksheet.

Site A: Wikipedia – Locard’s Principle 

On the Wikipedia site, click on the Dr. Edmund Locard link,

• Edmund Locard was the director of the very first _____________ laboratory in existence, located in Lyon, ______________.

• His exchange principle states that "with _________________ between two items, there will be an _____________________."

• _____________ __________________ is any type of material left at—or taken from—a crime scene, or the result of ________________ between two surfaces.

• Why is evidence placed in a paper bag or envelope rather than a plastic one? _____________________________________________________________________________ _____________________________________________________________________________

Use the excerpt from the article to answer the question.

“Use Ziploc bags for items, such as nuts and bolts, that won’t be processed further. Keep different sized bags on hand, since you want to match the item to the bag.

Paper should be used for items that need to breathe. Fingerprint evidence, pillows, comforters, etc. go in paper. Wet items go into paper. If you seal a bloody shirt in a Ziploc, it will putrefy and be ruined. Put bloody clothing into paper bags and transport to your station. While it’s drying, place white paper bags under the clothing to collect any trace evidence that falls. Retain the transport bag and white paper bags as evidence. Green marijuana also needs to go in a paper bag; if sealed in plastic, it will mold and won’t test properly.”

Site B: AC Trace Evidence 

• Hair is one of the most telling pieces of trace evidence that can be collected from a crime scene. Name two ways hairs may be used to help an investigation.

• a. ____________________________ ________________________________
• b. ____________________________________________________________

•  Fibers from ____________, carpet, ____________ and other sources that are foreign to the crime scene may indicate that the initial attack happened somewhere else, or might point to where the suspect ____________ or ____________.
• Shattered ____________ might indicate where a victim has been held, such as in a hostage situation, and ____________ chips might tell the investigators what kind of ____________ the suspect drives.

•  Dirt has different _________________ compositions in different areas of the same city and can tell investigators where a ____________ or ____________ has been. Similarly, certain kinds of dust – such as ____________ – can only be found in certain areas.

• Ballistics is the study of the marks and residue left by ____________ and ____________. A lot can be determined from the ____________ made by a bullet or by the gunshot ____________ on a victim’s skin.
• When a criminal uses a ____________ to break into a home, the type of tool used leaves tell-tale marks in ____________, metal, ____________ and other surfaces that can tell the investigators exactly what it was.

Site C: Hair Detective: https://www.sciencenewsforstudents.org/article/hair-detectives

Use this site instead of the one on the web page.

1. Scientists have found a way to use hair to figure out where a person is _________________ and __________________that person _____________________.

2. How do scientists use tap-water to figure out where a person is from?

3. How did scientists test to see if their idea would work? Did it?

4. True or False: The new technique can point to exactly where a person is from.

5. How do authorities use the information to solve crimes?

6. What advice is given by the scientists to the criminals?

.