Forensics - Chapter 11 Study Guide

1.Name the procedures or screening tests used for determining explosive residues.

2.What is the most widely used low explosive?

3.What device can be used to screen objects for explosive residue?

4.State the difference between a secondary and a primary explosive.

5.Why are taggants valuable in fire investigations?

6.Which type of explosive is common to Middle East terrorists?

7.Which type of materials are considered high explosives?

8.What rinsing agent can be used to recover explosive residues?

9.If spot tests are conducted, what confirmation test can be used?

10. What is the main focus of an investigator at a fire scene?

11. Name three reasons that speed imperative for arson investigators.

12. Define pyrolysis.

13. What methods can be used to detect hydrocarbon accelerants?

14. Define the flammable range.

15. What physical state must fuel be in for combustion to occur?

16. What instrument(s) is noted for being sensitive and reliable for detecting flammable residues?

17. Define flash point.

18. Define ignition temperature

19. Define combustion.

20. What factors contribute to abnormal observation at a fire scene?

21. What are some signs an investigator looks for when arson is suspected?

22. Describe the correct procedure for collecting evidence at a explosion crime scene. Chapter 11 Study Guide Answers 1. Name the procedures or screening tests used for determining explosive residues. Color spot tests, TLC, HPLC, GC, MS 2. What is the most widely used low explosive? Black powder and smokeless powder 3. What device can be used to screen objects for explosive residue? IMS - Ion mobility spectrometry 4. State the difference between a secondary and a primary explosive. Primary is sensitive to shock, heat and friction and will detonate violently instead of burning Secondary will burn rather than detonate and are insensitive to heat, shock, friction 5. Why are taggants valuable in fire investigations? Contains color coded chips that are fluorescent and magnetic sensitive and provide information about where it was made, trace chain of distribution 6. Which type of explosive is common to Middle East terrorists? TATP 7. Which type of materials are considered high explosives? ANFO, TATP, RDX, PETN, TNT 8. What rinsing agent can be used to recover explosive residues? Acetone 9. If spot tests are conducted, what confirmation test can be used? IR Spec, X-ray diffusion 10. What is the main focus of an investigator at a fire scene? Find the point of origin 11. Name three reasons that speed imperative for arson investigators. Evaporation of accelerant residues, safety and salvage, soil degradation due to bacterial activity, contamination of the scene. 12. Define pyrolysis. Decomposition of organic matter by heat, decompose the solid into gaseous products 13. What methods can be used to detect hydrocarbon accelerants? Portable vapor sensor or dogs 14. Define the flammable range. The range of possible gas or vapor fuel concentrations in the air that are capable of burning 15. What physical state must fuel be in for combustion to occur? Gaseous 16. What instrument(s) is noted for being sensitive and reliable for detecting flammable residues? Portable vapor detector 17. Define flash point. The minimum temperature at which a liquid fuel will produce enough vapor to burn 18. Define ignition temperature Minimum temperature at which fuel will spontaneously ignite 19. Define combustion. Rapid combination of oxygen with another substance accompanied by the production of heat and light 20. What factors contribute to abnormal observation at a fire scene? Drafts, winds, secondary fires due to collapsing floors and roofs, arrangement of the structure, stairways, and shafts; holes 21. What are some signs an investigator looks for when arson is suspected? Streamers, containers, ignition devices, breaking and entering, eyewitness interview 22. Describe the correct procedure for collecting evidence at a explosion crime scene. Disposable gloves, shoe covers, overall before beginning his search; Should have used a wire mesh screen to sift through the debris; all explosive evidence should be stored in airtight metal containers, not plastic; collect materials from immediate area and materials blown away from blast’s origin