External Post Mortem Artefact: A Key Issue in Hair Result Interpretation

The study reviewed the challenges of interpreting hair test results in post mortem cases due to potential external contamination from environmental sources or body fluids. Three cases were analyzed, showing consistent drug concentrations across hair segments, suggesting external contamination. Despite decontamination efforts, contamination from aqueous matrices like sweat and putrefactive fluids was difficult to remove. Experiments demonstrated that hair could test positive for drugs after being incubated in spiked blood, indicating that standard decontamination procedures were insufficient. The study concluded that homogenous segmental analyses might indicate external contamination, and a single hair result should not be used to assess long-term drug exposure. The presence of metabolites should not be relied upon for discrimination, as they can also originate from putrefactive material.