The Stability of Semen Stain on Different Kinds of Fabric Buried on Soil

¹ Master’s Degree in Forensic Science Multidisciplinary and Interdisciplinary School, Chiang Mai University, Chiang Mai 50200 Thailand
² Department of Forensic Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200 Thailand

^* Corresponding author, e-mail: supakit.kh@cmu.ac.th

Abstract

The forensic examination of semen is essential for criminal investigations in sexual assault cases. However, detecting semen on clothing is often challenging, especially when the body has been buried, due to environmental degradation and fabric type. Our study evaluates semen stain stability on different fabrics buried in soil. Semen samples were applied to cotton, polyester, and denim fabrics and buried in soil. Samples were collected at 0, 24, 72 hours, 7 days, and 14 days post-burial. Acid phosphatase (AP) activity and sperm count were analyzed as semen markers. Results indicated that both markers were detectable across all fabric types but exhibited varying degradation rates. Polyester showed the fastest decline in semen markers compared to cotton and denim fabrics. Environmental conditions, such as humidity, soil moisture, and pH, significantly influenced the persistence of semen evidence. Elevated humidity levels were associated with reduced AP activity, indicating more rapid degradation. These findings highlight that fabric type and environmental conditions critically impact semen stain retention and marker stability. The timing of evidence collection is crucial for reliable detection. Forensic investigations in sexual assault cases involving buried evidence should incorporate these variables to enhance the interpretation of semen component persistence and support justice outcomes.