Persistence of touch DNA on commonly encountered substrates in different storage conditions

• Published in: Forensic science international Vol. 348; p. 111728
• Main Authors: Kaesler, Todd, Kirkbride, K. Paul, Linacre, Adrian
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.07.2023; Elsevier Limited
• Subjects: Cotton fabrics; Deoxyribonucleic acid; DNA; DNA persistence; DNA quantification; Exposure; Forensic science; Forensic sciences; Genetic testing; Genotypes; Humidity; Rubber; Storage conditions; STR profiling; Substrates; Tactile stimuli; Touch DNA; Workflow; STR profiling; DNA quantification; DNA persistence; Touch DNA
• ISSN: 0379-0738; 1872-6283; 1872-6283
• DOI: 10.1016/j.forsciint.2023.111728

The persistence of touch DNA deposited after realistic handling of items typically encountered in forensic investigations has been the subject of few studies. Understanding the long-term persistence of touch DNA on different substrates in varying conditions can be central to the effective triage of samples for further processing. As the time between an alleged incident and collection of evidence may vary from a few days to years after an alleged event, this study assessed three different common substrates for the persistence of touch DNA over a time span up to 9 months. These substrates included fabric, steel, and rubber, each of which were handled in a way to imitate what may happen during a criminal act. The three substrates were exposed to two different environments for up to 9 months: inside a dark cupboard with no traffic to act as a control and an outside semi-exposed environment. Ten replicates from each of the 3 substrates were tested at 5 time points to create 300 samples. All samples were processed using a standard operating workflow to provide genotype data after exposure to different environments. It was found that the fabric samples produced informative STR profiles (defined here as 12 or more alleles) up to the 9 month timepoint for either environment. The rubber and steel substrates for the inside condition produced informative STR profiles up to the 9 month timepoint, but only generated informative STR profiles for the outside condition up to 3 and 6 months, respectively. These data add to our understanding of the external factors that affect DNA persistence. •All substrates generated highly informative STR profiles for the inside condition at 9 months.•Informative profiles were generated from the fabric substrate in the outside condition at 9 months.•DNA on steel and rubber substrates was affected by the environment in the outside condition.•Rubber was the poorest performing substrate in the outside condition.