Advanced putrefaction causes extensive loss of soft tissue, rendering it difficult to use the diatom test as a reliable diagnostic tool for drowning investigations. A positive diatom test in carrion insect larvae may provide significant assistance in overcoming the challenge of decomposition. The studies determined the utility of diatom test in carrion larvae on severely decomposed bodies. A modified acid digestion method involving nitric acid, K2Cr2O7 and HCl, was used to digest the blowfly larvae feeding on piglet carrion previously drowned in freshwater and sea water, respectively. Extracted diatom frustules were analysed and characterised using light microscopy coupled to a digital camera. Diatoms recovered from maggots on sea-drowned piglets were similar to diatoms from sea water (drowning medium). Centric diatoms recovered in maggots were higher (200 ± 60 diatoms/ mL) than pennate diatoms (80 ± 20 diatoms/mL). Isolated diatoms common to both maggots and water samples included Coscinodiscus sp. and Navicular spp. Albeit, there were no diatoms recovered from maggots on freshwater-drowned piglets. The findings of this study suggest that the diatom test is still a reliable diagnostic tool to determine if drowning was involved in the death of a fully decomposed body. This is the first study that isolated diatoms from maggots feeding on drowned bodies. It serves as the basis for further research into the utility of maggots for drowning investigations.
Keywords: Diatoms; cadaver; drowning; larvae; maggots; putrefaction.