A fatal case of Carbofuran and Para-phenylenediamine poisoning: A death mystery resolved

Abstract

This case study will be beneficial for the forensic toxicology community for simultaneous detection of carbofuran, a pesticide and para-phenylenediamine (a hair dye locally known as black stone) along with their metabolites in analytically challenging samples like liver tissue and stomach contents. A 35 years old married woman was killed by her family. As per police investigation, she had extramarital affair, which was against religious and social norms. Later on, she got divorced and tied a knot with a new husband. After two months, the female was found dead when she was at her parent's home. Her husband claimed that her father and brother poisoned his wife because they never accepted their marriage. The sudden death of a healthy female was full of doubt. Therefore, the police started an investigation. Postmortem of the deceased was performed immediately. Postmortem examination revealed that her right index fingernail was broken; the lips area was blackish in colour as well as suspected stains were found on her clothes. Biological samples like liver tissue and stomach contents along with her clothes were submitted to the author's laboratory to rule out the use of any poison or drug. The colourimetric screening was performed for locally available poisons like phosphine, cyanide and black stone. The modified QuEChERS technique was adopted for the extraction of an unknown drug or poison in challenging samples like liver tissue and stomach material. Extracts were analyzed on GC-MS. Para-phenylenediamine (>5000 ng/g) and carbofuran (>1000 ng/g) were detected in stomach contents and liver. Metabolites/breakdown products of para-phenylenediamine (monoacetylayed para-phenylenediamine) and carbofuran (carbofuran phenol) were also detected. Suspected stains on the victim's clothes were found to contain carbofuran. Carbofuran and black stone, both are deadly poisons and are easily available in local markets of Pakistan. In absence of any other pathological findings, detection of these poisons would be sufficient to establish the cause of death. According to the author's knowledge, this is the first case study in which carbofuran (pesticide) and para-phenylenediamine (a tasteless poison) along with their metabolites were detected and reported in postmortem samples. Forensic toxicology analysis played a key role in solving the mystery of a woman's death.