The use of fly artifacts in a crime scene: Is there any application for forensic toxicology?

Fly artifacts (FA) are bloodstains resulting from insect activity at a crime scene, usually by feeding on human blood. Whether these artifactual stains might be useful for forensic toxicological investigations in cases of absence of conventional and unconventional matrices, for example, in cases concealment of the body or of extensive putrefaction, has not yet been investigated. The purpose of this study is to understand if FA trace evidence permits toxicological analysis when traditional matrices are not available. To this aim, FA experimentally produced by Calliphora vomitoria feeding on human blood of a cocaine and heroin user were collected from absorptive and non-absorptive material. FA material was analyzed by a new simple and fast LC-MS/MS method. Results were evaluated in terms of presence of the drug and relative amount of the detected molecules. From a qualitative point of view, the analysis of FA revealed all the substances originally detected in post-mortem blood in both cases. The ratios of cocaine/benzoylecgonine, codeine/morphine, and 6-monoacetylmorphine/morphine recovered in FA from cotton-textile materials and from non-absorptive surfaces were consistent with data resulted from original post-mortem blood. The preliminary study herein reported demonstrated that FA are extremely informative in case of cocaine and heroin users and merit further research in order to be applied in real caseworks.