Persistence and detection of blood derived haemoglobin and DNA after attempted cleaning of crime-related items

This is the authors' abstract. We don't add key points for this paper.

Crime scene and evidence clean-up is commonly employed by perpetrators to conceal a crime and/or their involvement. Consequently, DNA and protein removal can result in loss of valuable evidence at serological and profiling stages of analysis. Depending on case circumstances, if negative blood detection tests are produced, some jurisdictions may not proceed to DNA analysis. Conversely, if a profile is generated after a negative blood test, the biological source may be misinterpreted. This study investigated the relative removal rates of haemoglobin and DNA derived from wet and dried blood deposited on two surface types following seven cleaning methods. Results of this study demonstrate that removal rates of haemoglobin and DNA are dependent on multiple variables including blood moisture, surface type and cleaning method/agents used. Overall, bleach and hot running water resulted in the greatest removal of haemoglobin from cotton and knife blades, whereas cold running water with sponge and bleach resulted in the greatest removal of DNA from cotton and knife blades, respectively. Consequently, this study expands our understanding of the persistence and detection of haemoglobin and DNA following different types of cleaning, which could elicit a re-evaluation of casework workflow and how evidence is interpreted in and out of court settings.