de Castro Therese C, Taylor Michael C, Kieser Jules A, Carr Debra J, Duncan W
Sir John Walsh Research Institute, University of Otago, Dunedin 9054, New Zealand; Institute of Environmental Science and Research (ESR) Ltd, PO Box 29-181, Christchurch 8540, New Zealand.
Institute of Environmental Science and Research (ESR) Ltd, PO Box 29-181, Christchurch 8540, New Zealand.
Forensic Sci Int. 2015 May;250:98-109. doi: 10.1016/j.forsciint.2015.03.004. Epub 2015 Mar 17.
Bloodstain pattern analysis is the investigation of blood deposited at crime scenes and the interpretation of that pattern. The surface that the blood gets deposited onto could distort the appearance of the bloodstain. The interaction of blood and apparel fabrics is in its infancy, but the interaction of liquids and apparel fabrics has been well documented and investigated in the field of textile science (e.g. the processes of wetting and wicking of fluids on fibres, yarns and fabrics). A systematic study on the final appearance of drip stains on torso apparel fabrics (100% cotton plain woven, 100% polyester plain woven, blend of polyester and cotton plain woven and 100% cotton single jersey knit) that had been laundered for six, 26 and 52 cycles prior to testing was investigated in the paper. The relationship between drop velocity (1.66±0.50m/s, 4.07±0.03m/s, 5.34±0.18m/s) and the stain characteristics (parent stain area, axes 1 and 2 and number of satellite stains) for each fabric was examined using analysis of variance. The experimental design and effect of storing blood were investigated on a reference sample, which indicated that the day (up to five days) at which the drops were generated did not affect the bloodstain. The effect of prior-laundering (six, 26 and 52 laundering cycles), fibre content (cotton vs. polyester vs. blend) and fabric structure (plain woven vs. single jersey knit) on the final appearance of the bloodstain were investigated. Distortion in the bloodstains produced on non-laundered fabrics indicated the importance of laundering fabrics to remove finishing treatments before conducting bloodstain experiments. For laundered fabrics, both the cotton fabrics and the blend had a circular to oval stain appearance, while the polyester fabric had a circular appearance with evidence of spread along the warp and weft yarns, which resulted in square-like stains at the lowest drop velocity. A significant (p<0.001) increase in the stain size on laundered blend fabric was identified. Bloodstain characteristics varied due to fibre content (p<0.001) and fabric structure (p<0.001). Blood on polyester fabric, after impact, primarily moved due to capillary force and wicking of the blood along the fibres/yarns, while for the cotton fabrics wicking was accompanied by movement of blood into the fibres/yarns. This study highlights the importance for forensic analysts of apparel evidence to consider the age, the fibre type and the fabric structure before interpreting bloodstain patterns.
血迹形态分析是对犯罪现场遗留血迹及其形态的研究。血液所沉积的表面可能会使血迹的外观发生变形。血液与服装面料之间的相互作用尚处于起步阶段，但液体与服装面料之间的相互作用在纺织科学领域已有充分的文献记载和研究（例如，流体在纤维、纱线和织物上的润湿和芯吸过程）。本文对在测试前经过6次、26次和52次洗涤循环的躯干服装面料（100%纯棉平纹织物、100%聚酯平纹织物、聚酯与棉混纺平纹织物以及100%纯棉单面针织织物）上的滴状血迹的最终外观进行了系统研究。使用方差分析检查了每种面料的滴速（1.66±0.50m/s、4.07±0.03m/s、5.34±0.18m/s）与血迹特征（母血迹面积、轴1和轴2以及卫星血迹数量）之间的关系。在一个参考样本上研究了储存血液的实验设计和效果，结果表明产生血滴的日期（长达五天）对血迹没有影响。研究了预先洗涤（6次、26次和52次洗涤循环）、纤维含量（棉与聚酯与混纺）和织物结构（平纹织物与单面针织织物）对血迹最终外观的影响。未洗涤织物上产生的血迹变形表明在进行血迹实验之前洗涤织物以去除整理处理的重要性。对于洗涤过的织物，纯棉织物和混纺织物的血迹外观呈圆形至椭圆形，而聚酯织物的血迹外观呈圆形，有沿经纱和纬纱扩散的迹象，在最低滴速下会形成类似方形的血迹。已确定洗涤过的混纺织物上的血迹尺寸有显著（p<0.001）增加。血迹特征因纤维含量（p<0.001）和织物结构（p<0.001）而异。聚酯织物上的血液在撞击后，主要由于毛细作用力和血液沿纤维/纱线的芯吸作用而移动，而对于纯棉织物，芯吸作用伴随着血液进入纤维/纱线的移动。这项研究强调了法医分析人员在解释血迹形态之前考虑服装证据的使用年限、纤维类型和织物结构的重要性。
