Forensic chemistry encompasses organic and inorganic analysis, toxicology, arson investigation, and serology. Each method of analysis uses specialized techniques and instrumentation. The process may be as simple as setting up a density gradient column to compare soil samples or as complicated as using a mass spectrometer or neutron activation analysis to characterize an unknown substance.
When volatile vapors burn above a flammable or combustible liquid-accelerant pool, they leave distinct burn patterns unlike other combustible products. The earlier a fire is extinguished, the more obvious these patterns will be. Except in the worst cases of destruction, there is still a chance of ignitable liquid residue recovery.
There are alot of ways to tell what kind of accelerant was used. A few ways to tell if a liquid ignition was used are; 1. Witness observations ("an odor and gasoline," etc.), 2. A low-pressure wave ("boom" or "whomp" sound at ignition), 3. Unnatural fire spread (downward, unusually fast, etc.), 4. Bright yellow/orange flames accompanied by black smoke, 5. Flames seen burning directly from the floor, 6. Localized "gapping" of wood or vinyl floor seams within the pour burn pattern, which may be caused by an ignitable liquid burning inside each joint or seam, 7. A "rainbow-colored" sheen on the surface of suppression water over the pour area, 8. Even height of smoke and heat patterns in the room of origin, 9. Accelerant containers in or near the scene, 10. Increased burn damage pattern at the bottom of furniture legs. boxes, etc., on the floor in the pour pattern area.
A forensic chemist's job is to identify and characterize the evidence as part of the larger process of solving a crime. Forensic chemists rarely conduct any investigative work; they handle the evidence collected from the crime scene. Understanding the evidence requires tools from many disciplines, including chemistry, biology, materials science, and genetics.