| Popis: |
Study Objective: To measure the effects of time and fabric composition on the ability of the forensic laboratory to recover and detect semen and sperm. Design: Samples of five different commonly used fabric types were treated with either human semen or egg-water mixture. The samples were submitted to the laboratory at different times, then analyzed for the presence of sperm, acid phosphatase, and enzyme p30. Setting: A forensic laboratory that evaluates a large number of kits collected from victims of sexual assault. Main Outcome Measures: Detection of seminal fluid and semen. Results: The overall accuracy rate was 96.0%, the false-negative rate 1.8%, and the false-positive rate 2.2%. There was no correlation between the lag interval from collection to evaluation and the likelihood of obtaining an erroneous result. Similarly, all commonly used fabrics were amenable for correct laboratory determination. Most erroneous findings occurred in the testing for acid phosphatase, which appears to be the least sensitive and the least specific method. In all but one case, visual identification of spermatozoa and the presence of enzyme p30 were accurate. Conclusions: The quality of physical evidence is not compromised by extended periods of time in storage. All three methods must be used to reduce the likelihood of an incorrect determination. |
