Effects of decomposition on the recoverability of biological fluid evidence.

The present research assessed how the physical and chemical changes associated with decomposition affect the detection and identification of blood and semen evidence, as well as subsequent DNA analysis. A feeder pig (postmortem interval (PMI) < 3 h) was placed within the Boston University Outdoor Research Facility for a period of 22 days. Human blood and semen were individually dispensed onto multiple areas of two cotton t-shirts; one layer of fabric was placed above and below the pig and a control.