9781422273449

Bringing Chemistry to the Crime Scene

From the moment a perpetrator enters a crime scene, they begin leaving behind traces of evidence that give away their identity, their behavior, and their instruments or weapons. From fingerprints and dirt tracked in on shoes to bullet casings, biological materials, and pieces of thread from clothes, these pieces of evidence—though microscopic—are invaluable to investigating and prosecuting crimes. To analyze these types of evidence, investigators rely on the help of forensic chemists, who may work in a variety of specialties, such as serology (the study of blood and other bodily fluids) and toxicology (the study of poisons). Using a range of laboratory equipment, tests, and scientific methods, forensic chemists help process and analyze physical evidence and samples collected from the victim’s body and the crime scene. While the term crime scene makes it seem that criminal offenses transpire in single locations, crime scenes can vary in size, depending on the nature of the crime and the behavior of the perpetrator. At the least, crime scenes include the precise location where the offense occurred, as well as entrances and exits from the area and any places where evidence can be found. For example, sometimes criminals use a vehicle to leave the location where the offense took place. If they’re transporting evidence— such as stolen goods or a victim’s body in the case of a murder—the vehicle would become part of the crime scene, along with any places where the evidence was taken or stored. For a suspicious fire, investigators would look at the entire structure and its perimeter to figure out how the fire could have been started and how it spread. With such a vast physical location to consider, it takes a keen eye and meticulous investigation to find samples of unknown substances that can be analyzed in a laboratory to provide important data for solving crimes.

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