Effect of Ageing of Seminal Stains on Their Detection on Fabrics In Criminal Investigations

Abstract

In sexual assaults the presence of semen on the crime scene, victim or suspect’s belongings acts as crucial evidence for establishing the occurrence of the crime. Fabrics are a common piece of evidence obtained at such crime scenes. The detection of seminal stain on a fabric depends on various factors such as absorption by the fabric, the colour and texture of fabric, the age of the stain, environmental conditions, etc. The current study was conducted on three different types of fabrics: cotton, nylon and denim and were exposed to a temperature of 25˚C for four different time durations- 1 day (24 hours), 3 days (72 hours), 5 days (120 hours) and 7 days (168 hours). Three different tests were performed on the samples to be tested. Accordingly, fluorescence test, Barberio’s test and Christmas tree staining test were carried out. It was determined that the fluorescence of the seminal stain increased with increasing time duration. The observations made in Barberio test was however, not seen to be affected by the time intervals. It was also observed that the sperm density was affected with increase of time of incubation of the seminal stains.

Keywords

• forensic science
• forensic serology
• seminal stains
• porous substrates
• ageing of stains