Persistence

The persistence of FDR on the hands has been studied by many workers and while there are wide variations in the literature (1 to 24 hours) the majority opinion is in the region of 1 to 3 hours from the event to the sampling of the suspect.177-179 Beyond 3 hours it is unlikely that residue will be detected on the hands of live suspects.

Persistence on face, head hair, and clothing has not been studied, but it is highly likely that FDR will persist on these areas for longer periods than on the hands.

Persistence data from casework experience are presented later.

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