Review Questions
1. How are fire scenes different than regular crime scenes for investigators? One reason fire scenes are different from regular crime scenes is that criminal won’t be present when the scene is discovered. Another reason is that fires and explosives cause serve damage to the crime scene, destroying evidence. With arson cases, they are a lot more limited than regular crime scenes. Test that can be performed are limited than with regular crime scenes. Search warrants aren’t needed to start investigating a fire scene. Investigators are also able to collect evidence at the scene without a warrant as well.
2. What is the blast effect? Blast effect is the outward rush of gases from the bomb’s site of origin can be as high as 7,000 miles per hour.
3. What are the two types of high explosives? Primary explosives are easily ignited and are very sensitive to heat and friction. These explosives are often used to help ignite other explosives. Secondary explosives are usually much less sensitive to heat and friction and they typically have to be ignited through the use of other explosive materials. Secondary explosives are often used to detonate buildings and include TNT and dynamite.
4. What is a substrate control? Why is it done? Substrate control is an uncontaminated sample that is taken from a scene. This allows forensic scientists to compare the two samples to better observe whether a flammable liquid is present. If only the sample taken from the point of origin shows a flammable liquid, it is more likely that the substance was used to start the fire.
5. How is the evidence from a fire scene collected? What should be avoided? Ash and soot are collected from where the fire is believed to have started. Any materials collected from a fire scene are placed in air-tight containers to prevent the further evaporation of any flammable liquid evidence. Depending on the size of the evidence, glass jars with lids and new, clean