Strengthening clothing damage analysis: quantification of stabbing force and weathering

Clothing damage analysis is a forensic discipline which provides mainly qualitative evidential value to criminal cases. This two-part investigation strengthens the value of clothing damage analysis through both quantitative and qualitative assessment. The aim of the first study was to determine whether the direction of a weapon (n=6) has any influence on the force required to penetrate a 50:50 polyester/cotton blend fabric. This was carried out at 2 speeds - 100mm/min and 2000mm/min - in a controlled manner using a universal strength tester. Only 2 weapons displayed any distinct differences in forces between some, but not all directions. The variability and overlap of results dictates that caution must be exercised when reporting on the force required to stab fabric. The cut lengths were examined to determine whether stab cuts lengths reflected the weapon width. The cuts were always smaller than the blade width and the bias cuts were always smaller than those in the warp and weft; this was due to the natural stretch which is more pronounced in the bias. The aim of the second study was to discover the evidential value of clothing damage after weathering. Stab cuts were created by different knives (n=2) into the same fabric draped over polystyrene, in the warp and bias directions. The samples were mounted and placed outside for periods of 1, 4 and 8 weeks. The damage was analysed through measurements of the cuts (quantitative), and the identity of the weapon was determined through the cut morphology (qualitative). The stab cuts lengths changed progressively through time, more so in the bias than the warp, but the weapon types remained identifiable. This outcome suggests that the evidential value of clothing after outdoor weathering remains high.