Rapid Documentation of Possible Semen Stains for Forensic DNA Profiling

The acid phosphatase (AP) test is widely utilised in forensic biology laboratories to examine for the presence of semen on crime evidence. If semen is present, the AP-positive areas are marked on the exhibit to indicate the precise location of the semen stain. However, documenting AP-positive areas with a crayon is time-consuming and laborious. In this proof-of-concept study, we evaluated the use of Saral Wax-Free Transfer Taper (TP) as an alternative tool for tracing the boundaries of AP-positive areas. We demonstrated that the TP pigment did not inhibit PCR amplification, as indicated by consistent internal PCR control (IPC) C_T values during real-time DNA quantification. While a reduction in DNA yield was observed under stress-test conditions, where TP pigment was intentionally included in the samples, complete STR profiles were still recovered with no allele dropout. Importantly, the documenting time for AP mapping was reduced by approximately five-fold with TP compared to crayon, underscoring its potential to enhance efficiency in forensic laboratory workflows.