Mass spectrometry-based proteomics for the forensic identification of vomit traces.

Proteomics was exploited to assess the nature of possible traces of vomit found on the scene of an alleged sexual assault. In the case in point, a woman reported to the police to be raped five days before by a cousin of hers in his car. The woman declared she had vomited in the car before fainting definitely, due to alcohol or possible drugs covertly slipped in her drinks. The suspect confirmed the sexual intercourse, but he claimed consensual sex while the woman was fully conscious. To establish consent and hence subsistence of the crime, the Magistrate requested toxicological analyses on items sampled from the car and from woman's boots. Negative results obtained from toxicological analyses could not exclude the actual assumption of psychoactive substances by the alleged victim, due to sample aging. On the contrary, proteomic analysis disclosed a pattern of 249 gene products including signature endogenous and food-derived proteins along with a multitude of peptide digests, clearly indicative of vomit, thereby supporting the victim's report in the case under examination. Proteomics also provided detailed information about the nature of meal, which might contribute to frame the crime scene in similar cases.