Forensic chemists and toxicologists work with drugs and poisons, but they each start with different evidence. Forensic chemists working in a crime lab must determine if the physical evidence they receive is an illegal substance such as marijuana or cocaine. They are also responsible for samples - including fire debris, soil, paint, glass, explosives, and fibers - obtained from suspected arson crimes. Toxicologists, on the other hand, work with biological evidence such as blood, saliva, urine, and feces, using analytical chemistry to identify chemical traces and unmetabolized drugs. They often work in labs associated with a medical examiner's office or a hospital. ""Drugs, Poisons, and Chemistry"" touches on all aspects of forensic chemistry.