Dr. Edmond Locard was a French criminologist, the pioneer in forensic science who became known as the "Sherlock Holmes of France". He formulated the basic principle of forensic science: "Every contact leaves a trace". This became known as Locard's exchange principle.
Edmond Locard
Forensic science, also known as criminalistics, is the application of science principles and methods to support legal decision-making in matters of criminal and civil law.
Ambroise Paré's surgical work laid the groundwork for the development of forensic techniques in the following centuries.
This is an example and explanation of extractor/ejector marks on casings.
Apparatus for the arsenic test, devised by James Marsh
Fingerprints taken by William Herschel 1859/60