Forensic genetic analysis of insect gut contents.

Entomological evidence is most often used for estimating the postmortem interval, but fly larvae can also be a source of vertebrate DNA. Forensic analysis of DNA recovered from a larva's gut can be used to identify what the larva had been feeding on. During our previous research studies, we used the same DNA extraction for the dual purpose of identifying the insect species and associating a maggot with its last meal. In our experience, we have encountered several situations where this method for associating a maggot with a corpse would have been useful, such as removal of remains from a suspected crime scene, an alternative food source is nearby the scene or the body, and a chain-of-evidence dispute. However, since maggot gut content analysis is a quite brand-new area of study, many of the limitations of the technique have not yet been explored. The results of our most recent research studies suggest that third-instar larvae actively feeding on the corpse can be considered the best source of human DNA, better than postfeeding or starved larvae. In this paper, the state of the art of forensic genetic analysis of maggot gut contents is reviewed.