Using mass spectrometry to transform the assessment of sexual assault evidence

The time-consuming analysis of sexual assault evidence creates a challenging bottleneck in forensic investigations. Common techniques for semen analysis result in sample destruction, and there are currently no confirmatory techniques for the preparation-free or in situ analysis of semen. In all, there is a crucial requirement for the development of faster direct analytical techniques. In this study, the first use of ambient ionisation mass spectrometry for the forensic analysis of human semen has been demonstrated. Sheath-flow probe electrospray ionisation mass spectrometry (sfPESI-MS) was applied to the analysis of semen for the purpose of rapid body fluid identification, in addition to determining the effects of sample age on detection. Fresh and aged semen were readily detected from numerous surfaces, with a preparation-free analysis time of <10 s. The technique was also applied to the analysis of different types of condom, demonstrating the ability to detect differences in sheath and lubricant compositions, essential evidence in sexual assault investigations. This demonstrates the potential to both indicate prophylactic use and ascertain information regarding the condom used.