Forensic Chemistry and Trace Evidence Analysis

Discussion

Reply to each topic with 250 word minimum:

· Hair as Evidence-Discuss hair as evidence and whether or not it can be identified as having come from a specific individual. What must the examiner rely on most?

· Hair Comparison Study-Summarize a study that provided valuable insight into the evidential value of hair comparison. What are the study's values and limitations?

Seminar

Trace Evidence

You have learned about the importance of trace evidence and the role that it plays in successful criminal investigations. Because trace evidence such as hairs, fibers and paint is routinely recovered from many different crime scenes, this type of evidence is routinely analyzed by forensic scientists.

Be prepared to discuss hair, fiber and paint evidence, their collection and how forensic scientists examine and compare these different types of evidence. What information can be obtained from these examinations to help police investigators solve crimes

Additional Seminar Information

To receive credit for the seminar if you are unable to attend, you are required to write a 300 - 500 word paper on the seminar topic above.

Assignment

Unit 7 Assessment: Hair Evidence and the Locard Exchange Principle Experiment

In this experiment you will begin with a microscopic examination of your own hair and also from pets in your home, if you have them. You will first become familiar with the class characteristics present in your hair and in animal hair.

In the second part of this experiment you will attempt to confirm the validity of the exchange principle through the examination of hairs.

Review Hair Evidence and the Locard Exchange Principle Experiment(Attached)

Discussion

· Example of a Porous Item-Give an example of some porous items that may be found at a crime scene and identify at least four different approaches for processing those items.

Discuss where you might expect to find each of these items at a crime scene and explain how that might affect your approach to processing the evidence. Use at least two credible sources beyond the material, yet with minimal quotations, to reference your work.

· Health Risk of Using Chemicals-Any time chemicals are being used, there is a health risk. Discuss the safety measures that should be used when applying powders, chemicals, and fuming techniques to evidence.

Seminar

Chemical Development of Fingerprints on Porous Items

This week's Seminar examines the broad topic of chemical development of fingerprints on porous items. You will explore methods such as ninhydrin, iodine, DFO, silver nitrate, and the use of alternate light sources for enhancement. Photography to preserve these chemically developed prints will also be covered.

Alternative to Seminar

To receive credit for the Seminar if you are unable to attend, you are required to write a 300-500-word paper on the Seminar topic above.

Assignment

Assignment 2: Water Experiment

In this exercise, you will determine the effects of water on latent prints.

· Take a drinking glass and handle it, making sure to leave fingerprint impressions on it.

· Immerse the glass in water for several hours.

· After a significant length of time, visually examine the glass and see if you can still see your fingerprints.

· Attempt this in a variety of conditions such as hot water, cold water, soapy water, or salt water.

· Keep notes on your results under each condition.

· Hypothesize reasons for similar and dissimilar results under the varying conditions.

Write a 1-2 page paper describing your experience as well as your results from this experiment.Directions:

Complete the worksheet.

Part One

Hair Sample 1:

1. What characteristics do you observe from the hair ?

2. What visual/microscopical characteristics do you observe ?

3. What is the length of the hair?

Hair Sample 2:

4. What characteristics do you observe from the hair?

5. What visual/microscopical characteristics do you observe?

6. What is the length of the hair ?

Part Two

7. How many hairs are present on each of the two tape lifts ?

8. How many appear to be animal hairs?

9. How many appear to be human?

10. How many of the human hairs appear different from your own hair?

11. Have you successfully confirmed the validity of the exchange principle?

Attachment:- Exchange_principle_experiment.rar