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Abstract
Criminals have long used fire to try to destroy evidence of other crimes. Historically this cover-up attempt has had enough success that today investigators may assume evidence has either been consumed by the fire or ruined by the fire-fighting efforts. Yet research indicates evidence can endure fire. Post-fire biological fluids have yielded partial or even full DNA profiles. However, there has been little investigation into the robustness of DNA from one biological fluid compared to another. In this study, I examined whether fire degrades the DNA from blood more than the DNA from semen by exposing the two fluids to fire, extracting the DNA from these samples using Qiagen kits, and measuring DNA degradation using real-time quantitative polymerase chain reaction. I quantified DNA from 59 post-fire samples plus 10 positive controls. Data analysis indicated the DNA degradation levels were not significantly different between blood samples and semen samples. However, DNA degradation levels varied significantly between samples on different substrates (nylon versus polyester).
