In recent decades, the use of entomology as a tool in forensic investigations has become fairly routine. The field of forensic entomology has a much longer history than you might suspect, dating all the way back to the 13th century.
The First Crime Solved by Forensic Entomology
The earliest known case of a crime being solved using insect evidence comes from medieval China. In 1247, the Chinese lawyer Sung Ts'u wrote a textbook on criminal investigations called The Washing Away of Wrongs. In his book, Ts'u recounts the story of a murder near a rice field. The victim had been slashed repeatedly, and investigators suspected the weapon used was a sickle, a common tool used in the rice harvest. How could the murderer be identified, when so many workers carried these tools?
The local magistrate brought all the workers together and told them to lay down their sickles. Though all the tools looked clean, one quickly attracted hordes of flies. The flies could sense the residue of blood and tissue invisible to the human eye. When confronted by this jury of flies, the murderer confessed to the crime.
Dispelling the Myth of Spontaneous Generation of Maggots
Just as people once thought the world was flat and the Sun revolved around the Earth, people used to think maggots would arise spontaneously out of rotting meat. Italian physician Francesco Redi finally proved the connection between flies and maggots in 1668.
Redi compared two groups of meat: the first left exposed to insects, and the second group covered by a barrier of gauze. In the exposed meat, flies laid eggs, which quickly hatched into maggots. On the gauze-covered meat, no maggots appeared, but Redi observed fly eggs on the outer surface of the gauze.
Establishing a Relationship Between Cadavers and Arthropods
In the 1700 and 1800's, physicians in both France and Germany observed mass exhumations of corpses. The French doctors M. Orfila and C. Lesueur published two handbooks on exhumations, in which they noted the presence of insects on the exhumed cadavers. Some of these arthropods were identified to species in their 1831 publication. This work established a relationship between specific insects and decomposing bodies.
Fifty years later, the German doctor Reinhard used a systematic approach to study this relationship. Reinhard exhumed bodies to collect and identify the insects present with the bodies. He specifically noted the presence of phorid flies, which he left to an entomology colleague to identify.
Using the Succession of Insects to Determine a Postmortem Interval
By the 1800's, scientists knew that certain insects would inhabit decomposing bodies. Interest now turned to the matter of succession. Physicians and legal investigators began questioning which insects would appear first on a cadaver, and what their life cycles could reveal about a crime.
In 1855, French doctor Bergeret d'Arbois was the first to use insect succession to determine the postmortem interval of human remains. A couple remodeling their Paris home uncovered the mummified remains of a child behind the mantelpiece. Suspicion immediately fell on the couple, though they had only recently moved into the house.
Bergeret, who autopsied the victim, noted evidence of insect populations on the corpse. Using methods similar to those employed by forensic entomologists today, he concluded that the body had been placed behind the wall years earlier, in 1849. Bergeret used what was known about insect life cycles and successive colonization of a corpse to arrive at this date. His report convinced police to charge the previous tenants of the home, who were subsequently convicted of the murder.
French veterinarian Jean Pierre Megnin spent years studying and documenting the predictability of insect colonization in cadavers. In 1894, he published La Faune des Cadavres, the culmination of his medico-legal experience. In it, he outlined eight waves of insect succession that could be applied during investigations of suspicious deaths. Megnin also noted that buried corpses were not susceptible to this same series of colonization. Just two stages of colonization invaded these cadavers.
Modern forensic entomology draws on the observations and studies of all these pioneers.