When postmortem intervals (PMIs) increase such as with longer burial times, human remains suffer increasingly from the taphonomic effects of decomposition processes such as autolysis and putrefaction. In this study, various DNA analysis techniques and a messenger RNA (mRNA) profiling method were applied to examine for trends in nucleic acid degradation and the postmortem interval. The DNA analysis techniques include highly sensitive DNA quantitation (with and without degradation index), standard and low template STR profiling, insertion and null alleles (INNUL) of retrotransposable elements typing and mitochondrial DNA profiling. The used mRNA profiling system targets genes with tissue specific expression for seven human organs as reported by Lindenbergh et al. (Int J Legal Med 127:891-900, 27) and has been applied to forensic evidentiary traces but not to excavated tissues. The techniques were applied to a total of 81 brain, lung, liver, skeletal muscle, heart, kidney and skin samples obtained from 19 excavated graves with burial times ranging from 4 to 42 years. Results show that brain and heart are the organs in which both DNA and RNA remain remarkably stable, notwithstanding long PMIs. The other organ tissues either show poor overall profiling results or vary for DNA and RNA profiling success, with sometimes DNA and other times RNA profiling being more successful. No straightforward relations were observed between nucleic acid profiling results and the PMI. This study shows that not only DNA but also RNA molecules can be remarkably stable and used for profiling of long-buried human remains, which corroborate forensic applications. The insight that the brain and heart tissues tend to provide the best profiling results may change sampling policies in identification cases of degrading cadavers.
Gunshot residue (GSR) and deoxyribonucleic acid (DNA) analyses are used in the reconstruction of shooting incidents involving firearms. In both fields, adhesive tapes are commonly applied to recover traces. Using a simultaneous sampling approach for retrieving both types of traces from objects related to a shooting can be powerful. We present the results for DNA testing and GSR analysis using “DNA stubs” to recover both types of traces in one sampling. The analyses are successive: stubs are first examined with scanning electron microscopy for the presence of GSR and next subjected to DNA extraction and short tandem repeat (STR) typing. The results show no negative effect on the DNA and GSR results. The risk of DNA contamination during GSR analysis is addressed, showing that it is negligible. Our experiences in casework show that the approach can be successfully implemented.
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