Human identification from washed blood stains

Abstract

BackgroundAmong the physical evidence, bloodstain is one of the most common biological pieces of evidence at the crime scene, especially in violent crimes. Bloodstains are frequently seen at the crime scene and can be easily detected due to their color and structure. Because blood and bloodstains can potentially be evidence of a crime, offenders often tend to clean or wash them to get rid of relevant evidence. Some researchers think that washed bloodstains cannot obtain enough quality DNA for DNA profiling. However, some studies have shown that bloodstains on a piece of fabric can be used for DNA profiling even after washing. This study, it is aimed to determine whether a sufficient amount of DNA can be obtained for DNA profiling used for forensic purposes from blood-stained nylon and cotton fabrics washed at different temperatures such as 40 °C, 60 °C and 90 °C.ResultsIn this study, bloodstains were created on cotton and nylon fabrics in a representative crime scene. After washing with laundry detergent at 40 °C, 60 °C and 90 °C was performed, studies were conducted in order to make bloodstains visible and obtain DNA for genetic profiling. The result is that more DNA is lost due to easy exposure to external factors in the non-absorbent nylon fabric type compared to the absorbent cotton fabric. Moreover, the rates of obtaining DNA from bloodstains on different types of fabrics washed at several temperatures are shown in this study.ConclusionsIt was determined that while a sufficient amount of DNA for the forensic genetic profiling can be obtained from cotton and nylon fabrics washed at 40 and 60 °C, a sufficient amount could not be obtained from the ones washed at 90 °C. And that shows even if bloodstained fabrics are washed at 60 °C, the fabrics still can be considered as physical evidence of the crime and can be associated with the scene, perpetrator and victim triangle.