Successful analysis of a 100 years old semen stain generating a complete DNA STR profile

Abstract

We performed forensic investigations on a handkerchief containing seminal fluid deposited 100 years earlier. The aim was to verify the possibility to achieve a complete genetic profile exceeding the limit of success reached until today with a partial semen stain profile stored up to 50 years. The current forensic methods were carried out: Alternative Light Source (ALS), Prostate-Specific Antigen (PSA) Test, autosomal and Y-chromosome Short Tandem Repeats (STRs). ALS inspection was a crucial method in the success of the analysis. On a dried semen stain, fluorescence remains constant for a very long time, allowing possibility to minimize the fabric sample to analyze, in order to preserve specimen for future defense guarantees or to protect historical finding. We achieved positive results in 3 of 6 traces, PSA and DNA results were concordant, only those cuttings that tested positive for PSA yielded DNA profiles. A complete male profile was generated by AmpFlSTR Identifiler Plus and 16 loci profile by AmpFLSTR Yfiler. Considering some historical sources that attributed this handkerchief dated 1916, to a famous Italian poet, the DNA profile found on the handkerchief was compared with a living male descendant, and the comparison of the Y-STR between the two gave positive results, confirming the reliability of the outcomes. The findings achieved by the current forensic method empower the application of this methodology to other forensic cases, especially in past unresolved cases.