Survival of spermatozoa on decomposing skin of sexual assault victims : a scanning electron microscopy study

In cases of sexual assault followed by homicide it may occur that traces of semen are present on skin (e.g. the abdomen, thighs, external genitalia) as well as or instead of in the vaginal or anal orifices. When decomposition sets in, standard methods of semen/spermatozoa detection (e.g. standard light mi- croscopy, immunological tests) may be inefficient on decaying skin. Inspired by findings on a real case where scanning electron microscopy (SEM) on the abdominal putrefied skin of a murder victim showed the presence of sperm-like formations when other assays for sperm turned out negative, the authors set out to test the survival of spermatozoa and their detectability by SEM on decaying skin. Furthermore, if decomposing remains are in an external environment, the situation may become even more diffi- cult due to the possibility of equally decaying microorganisms and protozoa mimicking cellular structures. This presentation therefore exposes the results of two experiments aimed at observ- ing the microscopic survival and morphology of spermatozoa on decomposed skin by SEM and the possibility of microorganisms mimicking sperm parts.