Time since intercourse (TSI) data from a large-scale casework study of penile-vaginal penetration allegations using...

Time since intercourse (TSI) expectations are dependent on the method used to recover spermatozoa from vaginal swabs. TSI data following Sperm Elution™ is presented from a large scale study of 2269 cases of penile-vaginal penetration sexual assault allegations analysed by Cellmark Forensic Services and is compared to published TSI data generated using two different water-based elution methods Sperm Elution recovered spermatozoa in 32% of cases analysed where the alleged offence had occurred 3-4 days previously, significantly above the level detected using other elution methods. The improvements afforded by Sperm Elution in the ability to generate clearly distinguishable male DNA profiles from samples containing low levels of spermatozoa, and the recovery of further spermatozoa from swabs previously subjected to water-based elution methods are also discussed.