Heroin markers in hair of a narcotic police officer: active or passive exposure?

On March 2007, a police officer (46-year-old man) and a clerk (37-year-old woman) were arrested and subjected to investigation on the charges of drugs of abuse trafficking. The loving couple was exploiting their administrative positions to make money with the resale of seized drugs. The laboratory was requested to analyse their hair for drugs of abuse. Hair of the 2 subjects tested positive for heroin by GC-MS. A few days later, analysis of hair obtained from 11 other police officers of the same unit was requested, in order to compare the results, as external contamination was proposed to account for the positive results. The aim of the investigations was to demonstrate that passive contamination could not occur for persons dealing every day with drugs of abuse with minimal caution and hygiene, and that the measured concentrations in the arrested subjects correspond to personal abuse. All the narcotic team tested negative, irrespective of the compound.