Diatom analysis: Reviewing the strengths, weaknesses, and impact of modern research

Abstract

The purpose of this paper is to review the theoretical and laboratory techniques which underpin diatom analysis and its ability to help determine death by drowning in a forensic context. Diatom analysis involves the recovery of diatoms (unicellular algae present in most natural bodies of water) which may be inhaled as part of a drowning medium (water) by an individual who has drowned prior to death. This literature review evaluates the strengths and weaknesses of the diatom analysis technique in the forensic context and evaluates recent research to discern whether it can be considered a reliable and valid forensic technique today. It is important to establish clarity, as much of the original research conducted throughout the 1970’s, 80’s, and 90’s have conflicting conclusions regarding the validity and reliability of diatom analysis. This literature review will show that modern research techniques used as part of the diatom analysis method have been able to reduce false positive results, increased the ability to distinguish between true and false positives, and found ways to mitigate many of the weaknesses noted in earlier research. Although some weaknesses such as diatom introduction into bodies prior to death and some details surrounding false positive results remain outstanding concerns, it can be seen in the literature that, when combined with existing strengths like seasonal variability and environmental specificity, diatom analysis is a valuable forensic tool, whose reliability has been strengthened by modern research, and can be relied upon to establish a definitive diagnosis of death by drowning.