The recovery of semen from bath scrunchies

Nucleic Acids Persistence-Benefits and Limitations in Forensic Genetics

The analysis of genetic material may be the only way to identify an unknown person or solve a criminal case. Often, the conditions in which the genetic material was found determine the choice of the analytical method. Hence, it is extremely important to understand the influence of various factors, both external and internal, on genetic material. The review presents information on DNA and RNA persistence, depending on the chemical and physical factors affecting the genetic material integrity. One of the factors taken into account is the time elapsing to genetic material recovery. Temperature can both preserve the genetic material or lead to its rapid degradation. Radiation, aquatic environments, and various types of chemical and physical factors also affect the genetic material quality. The substances used during the forensic process, i.e., for biological trace visualization or maceration, are also discussed. Proper analysis of genetic material degradation can help determine the post-mortem interval (PMI) or time since deposition (TsD), which may play a key role in criminal cases.

Evaluating the persistence of laundered semen stains on fabric using a forensic light source system, prostate-specific antigen Semiquant test and DNA recovery-profiling

Semen stains on the clothes of victims of sexual assault can remain as evidence even after garments have been laundered. In this study, we aimed to investigate the effectiveness of commonly preferred methods to detect semen stains in two different fabric types that were laundered with different washing machine programmes and washing powders, and to obtain a DNA profile from the semen stains. For this purpose, a comprehensive study was performed on semen-stained underwear using three different methods for stain detection, confirmation and identification: a forensic light source (FLS) system, the prostate-specific antigen (PSA) test and DNA recovery profiling. With FLS applications, stronger fluorescence was achieved in wash protocols performed at a low temperature (30°C) on semen-stained cotton underwear. DNA recovery between 13.45 and 55.00 ng/µl was obtained by modifications in the DNA extraction step when the effect of temperature and washing powder on DNA recovery was evaluated, and these were enough for short tandem repeat (STR) typing in all samples. This study shows that when semen-stained underwear is washed after a month, some semen stains can be determined by FLS and PSA, and all stains can be identified by STR analyses.