The recovery of semen from bathwater using the Evidence Recovery System (ERS)

Abstract

Sexual offences are under-reported and ascertaining accurate offence numbers is difficult. Any methods which could increase the ability to obtain biological evidence or reduce the additional distress associated with reporting a sexual offence may result in an increase in reporting this crime type. The Evidence Recovery System (ERS) is designed to collect trace evidence, including hairs, fibres and biological evidence, from bath or shower water in a non-invasive manner. Initially, samples of semen were placed in baths filled with water, and washing was simulated using a range of body wash products. The water was then drained through the ERS before its filters were subjected to acid phosphatase testing and haematoxylin and eosin staining of spermatozoa. Recovered spermatozoa were then graded accordingly. Following this, the experiment was repeated with the addition of dirt/dust particulates during the washing stage, to simulate recovery of biological evidence in a more realistic environment. The results showed that spermatozoa considered 'easy to find' could regularly be obtained from bathwater using the ERS. It appeared that this recovery was not affected by the presence of different body wash products. When dust/dirt particles were added, the number of spermatozoa recovered increased at two of the evidence collection stages. The difference in recovery was considered to be statistically significant. This study provides evidence to suggest the feasibility of use of the ERS as a method to collect semen evidence from individuals subjected to sexual offences. The recovery of spermatozoa does not appear to be affected by the presence of a body wash, but does appear to be improved when skin cells, hair and other debris are transferred into the water, as would be likely during a bath/shower. Further to this, the possibility of obtaining spermatozoa from the home bath or shower of a victim following a post-offence bathing experience is implied.

DNA/RNA co-analysis of seminal fluid-stained fabrics after water immersion for up to seven days

“…The comparison of BFI methods (Table 1) shows that Phosphatesmo failed to detect seminal fluid in all samples. This observation is concordant with other studies that investigated water-exposed seminal fluid stains [6,7]. The Phosphatesmo test is used to detect acid T phosphatase (AP) in seminal fluid stains.…”

The recovery of semen from bath scrunchies

“…Extending this time period may well see the detection of AP reduce as a consequence. Irrespective of the AP results, the recovery of spermatozoa from 99% of the samples aligns with previous work showing that spermatozoa recovery is possible even with negative AP results 14,[19][20][21] . When positive, the recovery of spermatozoa did vary across all four scoring categories with a reduction in recovery rate as the quantity of sample decreased when analysing the rope.…”

“…Obtaining 77% positive AP results from the net and rope components of the bath scrunchies appears to be a much higher detection rate to that previously observed in the literature 14,[19][20][21] . Davidson & Jalowiecki 23 observed diffusion of seminal stains when fabric was wetted prior to AP testing.…”

“…AP testing is the standard protocol used for presumptive testing of semen 18 . Detection of AP after washing has occurred is reported to be difficult, due to its water-soluble nature [19][20][21] , but some success has also been observed 14 . It is possible to recover spermatozoa from a variety of washed sample types and from bathwater 14,[19][20][21] , even those testing negative for AP 13 , so staining for the identification of spermatozoa was completed for all samples irrespective of their AP result.…”