Drugs, pesticides and metabolites in forensic post-mortem blood samples

Forensic post-mortem toxicological data provide valuable information for the elucidation of cause of death. However, this is still not routine practice in Brazilian laboratories. This study investigated the presence of illicit and prescription drugs, pesticides and metabolites in 111 post-mortem blood samples from cases investigated by the Forensic Medical Institute of the Federal District, Brazil. Quantitative analysis was performed for 14 analytes using a validated programmed temperature vaporisation-large volume injection-gas chromatography-mass spectrometry method, which was also used as screening (qualitative analysis) for an additional 19 substances of forensic interest. At least one analyte was found in 61.2% of the samples, of which 34 were related to homicide, 15 to accidental death and 10 to suicide cases. The victims were 14-72 years old. The benzodiazepines diazepam, midazolam and 7-aminoflunitrazepan were detected in 46% of the positive samples (0.02-1.12 µg/mL; midazolam only qualitative). Cocaine was found in 34% (0.02-4.07 µg/mL), associated with substances commonly used as cocaine adulterants (e.g. caffeine, lidocaine and phenacetin). Three suicide cases involved the illegal rodenticide chumbinho, residues of which were found in the gastric content, and blood samples showed the presence of terbufos (0.03 and 0.04 µg/mL) and carbofuran (27.3 µg/mL). These results are discussed, along with autopsy and crime-scene information.