Questioned gastric content: analysis of human STR polymorphisms and scanning electron microscopy study

In April 2011, the corpse of a young woman, who disappeared two days earlier, was found in a forest in Ripe di Civitella del Tronto (Provice of Teramo, Italy). The conclusions of the first medicolegal consultants were widely disputed, so the Judge for the Preliminary Investigation of the Court of Teramo asked our laboratory to review the case. One of the most debated topics was the gastric content of the death woman. Its description greatly varied during the previous investigations. Accordingly, many questions arose regarding the identification of the food ingested during her last meal. Since the gastric content is an important element for the evaluation of the time of death, it was necessary to undertake further investigation. First of all, to make sure that the specimen belonged to the young woman, we took about 100 microliters of the gastric content for forensic genetic investigation. The sample was extracted, quantified with Real-Time PCR and typed with the commercial kit “Investigator ESSplex ® Plus” (Qiagen). The resolution of the amplicons was achieved by capillary electrophoresis (ABI PRISM 310 Genetic Analyzer - Applied Biosystems). Then, we conducted an analysis of electrophoretic data sample with GeneScan and Genotyper 3.7 softwares (Applied Biosystems). Finally, we compared the genetic profile obtained from the gastric content with a positive outcome with the genetic profile of the victim typed in the course of the previous investigations. After we established that the gastric content actually came from the woman’s stomach, we first proceeded by visual inspection. The material clearly appeared liquid with the presence of frustules of light brown, hard consistency, not previously described. The frustules were placed on a glass slide that was directly inserted into the chamber of a variable pressure scanning electron microscope LEO 1430 VP. This procedure allowed us to identify some material as tiny bits of almond. The mother of the young woman reported that sometimes her daughter fed on milk and cereals and during the inspection, some muesli with almonds was actually found in the kitchen. Moreover, the examination of a smear test carried during the previous forensic investigations of the gastric content also revealed the presence of lipid droplets and starch grains. All these elements combined together allowed us to conclude that the last meal eaten by the woman consisted of milk and muesli.