Evidence Collection


  1. How far down in the trace layers does an investigator want to go?

Investigatorsconsider various levels of traces that can generate new evidence.Therefore, they should go as far as he can deduct new evidence.

  1. How often should you collect alibi samples?

Alibisamples are important in supporting a case. An investigator should,therefore, collect the specimen as regularly as a possible to formconcrete evidence (Girard,2013).

  1. What is the only way that glass can be individual evidence instead of class evidence? What about hairs: how can you individualize them? And, last, how do you individualize fibers?

Glassis considered to be class evidence when there are no fittingfragments. Conversely, when forensic investigators find matchingfragments, they take the evidence to be individual. Hair is onlyclassified as class evidence when it does not have the follicles(Girard,2013). However, with the follicles, it can be used to identify aspecific person, and it can, therefore, be admitted as individualevidence. Fibers can be individualized when they match o if there isblood, paint of any other material absorbed in the fibers(Girard,2013).

  1. Discuss the proper collection of evidence at the origin of a fire that is suspected of being initiated by gasoline. Describe the proper submission of controls for laboratory examination.

Aproper collection of evidence would include accumulation of severalquantities of ash and soot, taking pictures, notes and sketching thescene. Also, the investigator should collet any flammable liquid fromthe scene and put it in an airtight container. Finally, he/she shouldcollect controls and label all the containers before submitting themfor analysis (Dror,2015).

  1. What are the two classes of high explosives? What is the difference between the two classes?

Highexplosives are categorized as primary and secondary. Primary highexplosives are unstable and ultra-sensitive to heat. Conversely,secondary high explosives are stable and insensitive to variousfactors including heat, shock, and friction (Girard, 2013).

  1. What are some common household items that can be mistaken for accelerants?

Theitems include printed materials, adhesives, and floorings.

  1. If you have a positive GSR, does that mean that you have recently shot a firearm?

Apositive GSR does not necessarily mean that one has recently shot afirearm. The rationale for this is that the residue can remain on theclothes or the body for a long time (Girard, 2013). In addition, aperson who comes into contact with an individual who has fired afirearm might test positive for GSR.


Saferstein,R. (2015). Forensic science: from the crime scene to the crime lab.New York N.Y.: Pearson.

Girard,J. E. (2013). Criminalistics: Forensic science, crime, and terrorism.Burlington: Jones &amp Bartlett Publishers.

Dror,I. (2015, May). Recognition and Mitigation of Cognitive Bias inForensic Science: From Crime Scene Investigation to Forensic Researchand Literature. In Forensic Science Research and Evaluation Workshop(p. 53).