THE QUANTITATIVE ALTERATION OF THE DNA CONTENT IN STRANGULATION MARKSIS AN ARTIFACT

It is frequently difficult to prove the vitality in cases of fatal han ging. Using impulse cytophotometry, Muller et al. (Krim. Forens. Wiss. 44, 1981) reported on possibly vital alterations of the DNA content i n five strangulation marks (hypodiploidy). The objective of the presen t study was to perform a re-evaluation by means of current methods of quantitative DNA analysis. The investigation included 24 cases of hang ing (typical, n=11; atypical, n=13). DNA was extracted by use of pheno l/chloroform and quantitated photometrically in relation to the tissue weight. In addition, skin specimens were examined histologically and their water content was determined. The mean DNA content of strangulat ion marks was 3.2 mu g DNA/mg tissue, that one of uninjured skin (cont rol) 1.4 mu g DNA/mg tissue. The ratio of DNA content between strangul ation grooves and control skin varied from 1.2 to 5.2 (average: 2.4) i mplicating apparently elevated DNA levels in strangulation marks. Hist ology revealed typical changes with absence of leukocyte infiltration suggesting mechanical compression of DNA containing layers. The additi onal determination of the water content emerged - in dependence on the macroscopic appearance, dried or non-dried reduced values for strangu lation marks (average: 42% vs. 66%). Statistical analysis demonstrated a significant correlation between elevated DNA content and reduced wa ter content of strangulation marks. Conclusion: the markedly elevated DNA content of strangulation marks is interpreted as an artefact due t o drying of the skin with a reduction of the water content (and weight ) in the course of mechanical cutaneous alterations (compression). The refore, quantitative changes in the local DNA content of the groove ha ve no importance as a sign of vitality in fatal strangulations. (C) 19 97 Elsevier Science Ireland Ltd.