The indirect transfer of glass fragments to a jacket and their subsequent persistence

Experiments were conducted to investigate a scenario sometimes encountered in casework, where a police officer has attended a scene and shortly afterwards arrested a suspect. The experiments involve the transfer of glass fragments from a surface scattered with broken glass to a hand, and then from the hand to the sleeve of a poorly retaining jacket. The persistence of the transferred fragments was studied by collecting the glass fragments as they fell off the jacket, whilst the wearer was walking on the spot. The recovery regime allowed the number and proportion of fragments picked up and transferred to the jacket from the hand to be determined, and the rate at which they were lost from the jacket to be monitored. The results show that large numbers of glass fragments can be picked up on a hand from a suitable surface. A subsequent firm grip to a poorly retaining jacket was found to transfer a significant proportion of the glass fragments from the hand to the jacket. In seven of nine tests performed, ten or more glass fragments were recovered from the jacket 60 minutes after the original contact between the hand and the broken glass. More than twenty fragments were recovered in three of these tests. Consequently, where possible and appropriate, the full circumstances of a case should be considered carefully before indirect transfer is ruled out as a possible explanation for recovered “matching” glass. This is the case even for poorly retaining clothing.