The Significance of Fibre Transfer and Persistence – A Case Study

In April, 1995 the body of a young woman was found in a suburb of Sydney, Australia. The body was fully clothed and bore a number of injuries to the neck, face and fingers. There were no signs of sexual assault and she appeared to have been strangled. The only physical evidence located at the scene was a number of dark, coarse fibres adhering to the soles of her shoes. These fibres consisted of 9 grey polypropylene, 12 blue polypropylene and 50 black polyester. The source of these fibres was found to be the carpet of a 1991 Honda CRX that belonged to the suspect. Almost all other possible sources of these fibres were eliminated. At trial the source of the fibres was not disputed by the defence. Instead the issue became how long these fibres had persisted on the shoe soles. A number of experiments were conducted to investigate the factors influencing the transfer and persistence of carpet fibres to shoe soles and the results of these experiments became a critically important part of the prosecution.