Diatom analysis in victim's tissues as an indicator of the site of drowning.

The diagnosis of drowning is one of the most difficult in forensic pathology and previously we proposed criteria for a positive tissue analysis according to the qualitative and quantitative diatom investigations. In the positive cases, we studied the reliability of determining the site of drowning by comparing the diatom taxa found in the lung samples with those of the water samples or in the absence of these samples with the results of the water diatom monitoring programme set up in our region. In this study, we present two series of cases, the first is one of 20 corpses who died from accidental or suicidal drowning with known drowning site, and the second of 20 corpses for which the drowning site was unknown. The results showed that a concordance of the abundance of the diatom taxa in tissues compared to the site of drowning and their distribution relative to one another was 65% in the group where the site of drowning was known and 35% in the other group. The concordance of the individual distribution in the lungs of water diatom taxa may be an interesting method to guide the investigations for determining the site of drowning. The two limiting factors are the concentration of diatoms in the lungs and the development of a river monitoring programme in the district of the study.