An investigation into secondary transfer-The transfer of textile fibres to seats

Textile fibres can be transferred directly, person to person or person to scene (primary transfer), or indirectly via an intermediate (secondary transfer). In criminal cases involving a transfer of textile fibres, it is often the case that whilst the provenance of recovered 'crime significant' fibres is accepted by the defence, it is a particular activity leading to their transfer to a surface in question which is disputed. In such circumstances, transfer and persistence studies relating to fibres on a particular substrate in particular conditions assist in evaluating whether the presence of crime relevant fibres is more likely to have occurred by one particular activity compared to another. This study investigates the effect of a time delay between the primary transfer of fibres to a garment on the numbers of subsequently secondarily transferred fibres to a seat. Two donor garments composed of polyester and cotton fibres respectively were employed in this study and secondarily transferred to seats after time intervals of 0, 0.5, 2, 6 and 24h. The number of secondarily transferred fibres were recorded according to fibre type and time interval and compared against levels recorded at the primary transfer stage. The results showed that only a relatively small percentage of the original primary transfer is likely to be secondarily transferred and that the numbers found were inversely proportional to the time interval between the primary and secondary transfer. In addition, it was found that the secondary transfer of cotton fibres was an order of magnitude higher than for polyester.