The earliest method of forensic science in an investigation was used in China. Pigs were put into a small enclosure, set on fire, and cut open to see if the effect of burning matched the effect of burning on a human.
People accused of being guilty for a crime would undergo torture, and were only proven innocent if God gave them strength to resist the pain from torture.
A Swedish chemist who devised a test for detecting Arsenic in dead bodies. In 1806, Valentin Ross discovered a more precise method for detecting small amounts of Arsenic.
Mathieu Orilla, also known as the "Father of Forensic Toxicology" publishes an article on detection of poisons and effects.
Photographs were beginning to be used in investigations for more accurate recordings.
Alphonse Bertillon introduces the Bertillon system, also known as Anthropometry. The system identified people based on their physical appearance. It was later replaced by fingerprinting in 1903.
"Criminal Investigation" by Hans Gross is published, the first book of criminal investigation using forensic science.
ABO blood typing discovered by Karl Landsteiner.
"Questioned Documents" published by Albert Osborn.
Locard's Exchange Principle by Edmond Locard
When two objects come into contact with each other, a cross-transfer of materials occurs that can connect a criminal suspect to the victim or the crime scene. Locard also started the first known police crime lab.
Los Angeles PD Crime Lab opens, first crime lab to open in the USA.
FBI National Laboratory opens under Director J. Edgar Hoover in Quantico, VA.
"Father of Modern Microscopy" McCrone furthered the understanding of light microscopes for material analysis.