Analysis of Mitochondrial DNA from a Burned, Ninhydrin-Treated Paper Towel.
Contact-based evidence is likely to have limited quantities of DNA and may yield mixed profiles due to preexisting or contaminating DNA. In a recent arson investigation, a paper towel was collected and used as circumstantial evidence. The paper towel was partially burned and was likely set on fire with flammable liquid. As part of the investigation, the paper towel was treated with ninhydrin to visualize fingerprint evidence. Initial DNA analysis of two swabs was negative for short tandem repeat (STR) markers and revealed a mixture of mitochondrial DNA (mtDNA). Analysis of 13 additional cuttings yielded four more mixed profiles, but also two samples with a common single-source profile. The single-source mtDNA profile matched that of the primary suspect in the case. Thus, even if initial mtDNA analysis yields a mixed profile, a sampling strategy involving multiple locations can improve the chance of obtaining valuable single-source mtDNA profiles from compromised evidence in criminal casework.
Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Box 815, S-751 08, Uppsala, Sweden.
Magdalena M
MM
Buś
Swedish Police Authority, Stockholm Region, Division of investigation, Forensic Section, S-106 75, Stockholm, Sweden.
Martina
M
Nilsson
Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Box 815, S-751 08, Uppsala, Sweden.
Marie
M
Allen
DNA typing; forensic science; mitochondrial DNA; mixed mtDNA profile; ninhydrin; paper towel; trace DNA