The Effect of Laundering on the Detection of Acid Phosphatase and Spermatozoa on Cotton T-Shirts

Abstract

ABSTRACTIn sexual assault cases, items submitted for forensic analysis are frequently examined for seminal fluid. The contents of a medical examination kit taken from the victim, particularly the genital swabs, are often the main source of associative DNA evidence. Depending on the circumstances, however, the examination of clothing and bedding can also be important. A standard procedure used in searching clothing is to screen for acid phosphatase and to confirm the presence of seminal fluid by examination for spermatozoa. It is frequently assumed that laundering the item in question will remove acid phosphatase and therefore testing for this enzyme is not useful. We have washed and laundered seminal stains on cotton T-shirts in a variety of ways, including dry cleaning. The cleaned fabric was screened for acid phosphatase, and the presence of spermatozoa determined. The DNA content of the cleaned stain was quantified and Short Tandem Repeat (STR) profiles were obtained using the CTT triplex. The results obtained are discussed in the context of the overall examination tactics in sexual assault cases.