This paper describes the application of hair analysis in a judicial case to document coercive heroin administration to a 5-year-old child, who was admitted with overdose symptoms to an intensive care division. Segmental hair analysis was performed in order to determine if drug consumption had continued. Quantitative results showed the presence of morphine and O-6-monoacetylmorphine (MAM) in increasing amounts from the second to the distal segment of hair, each approximately corresponding to a period of time of one month. MAM concentrations ranged from 0.2 ng/mg in the second segment of hair to 0.6 ng/mg in the distal segment; morphine concentrations ranged from 0.1 to 0.3 ng/mg. Limits of detection were 0.1 ng/mg for morphine and 0.2 ng/mg for MAM. The proximal segment of hair, which corresponded to the period that the child was housed in a social center, was negative for opiates.