Some crime scenes don’t have bodies. What they have is a place where a body was, and a suspiciously large amount of maggots. Up until recently, the maggots could only have been a very bad sign. Now, it seems that maggots can help genetically identify their last meals.
According to the case studies in this paper on forensics, murderers really don’t want to get caught. To keep from being caught, they will happily move a body, bury a body, or even burn down their house and pretend that the body inside it perished in the fire, instead of several days before the fire. In each case, while the bodies didn’t provide clues, the insect life that had fed on the body did. The concentration of maggots was an indication that something had gone down, even if it wasn’t conclusive evidence all on its own.
That can change. Maggots unlucky enough to be found on murder scenes have sometimes been mashed up for DNA, but it was always their DNA. Different maggots have different incubation times, so figuring out what species of insect is living on a corpse can help investigators narrow down time of death. Then someone got an idea. When maggots feed they store some of their meal in an organ called a “crop.” Extracting the contents of the crop might allow investigators to know whether maggots present at a potential crime seen had been eating a dead rat or bird, or if they had been eating human flesh.
Researchers grabbed some maggots, and a piece of human liver that had come from a transplant patient. They fed the maggots on the liver for a few days, then plucked them off and extracted material from their crops. The scientists found that mitochondrial DNA “could be used to identify both the human corpse upon which the maggot had been feeding and the species of maggot itself.” Although the researchers aren’t sure about the time limit on the maggot identification system, they believe this could be a good way to disprove claims that the presence of maggots at a scene is incidental, or that the maggots had been feeding on some other material.