You are what they eat (Image: Frank Greenaway/DK/Getty)

WHEN Mexican police found a body in the woods it was burned beyond recognition, its DNA too damaged to be used for identification. Luckily, investigators were able to extract DNA from elsewhere – the digestive systems of maggots that had been feeding on the body. This is the first time that human DNA from a maggot gut has been analysed in this way to successfully identify a victim in a legal case.

Police suspected that the body was that of a woman who had been abducted 10 weeks earlier because they found her high-school graduation ring near the crime scene. But when forensic investigators failed to obtain a decent DNA sample from any of the body’s tissues, they turned to a team of pathologists at the Autonomous University of Nuevo León in San Nicolás, Mexico.

María de Lourdes Chávez-Briones, Marta Ortega-Martínez and their colleagues dissected three maggot larvae collected from the body and extracted the contents of their gastrointestinal tracts. The human DNA they isolated allowed them to determine that the body was female. They then performed a paternity test between this DNA and that of the abducted woman’s father. It revealed a 99.7 per cent chance that she was his daughter (Journal of Forensic Science, doi.org/jdv).


Although it is rare for a body to be so damaged that investigators would have to resort to this technique, there are other instances in which the process could be useful, says Jeffrey Wells of Florida International University in Miami. For instance, a maggot found in a car could be used as evidence that the vehicle had been used to transport a particular corpse.

The past decade has seen a lot of research on isolating human DNA from insects, says Martin Hall of the Natural History Museum in London, but it has only rarely been used in courts. Last year, DNA from the guts of maggots found on a headless corpse and on a head discovered nearby were used as evidence in a Chinese court that the body parts were from the same person (Tropical Biomedicine, vol 28, p 333).

The investigators extracted DNA from the guts of maggots that had been feeding on the body

Insects at crime scenes are too often ignored, says Hall. He hopes that the new paper will alert police and pathologists to their potential as crime-fighters.