Cranfield Defence and Security, Cranfield University, Shrivenham, Swindon Wilts SN6 8LA, UK.
Cranfield Defence and Security, Cranfield University, Shrivenham, Swindon Wilts SN6 8LA, UK.
Forensic Sci Int. 2022 Dec;341:111515. doi: 10.1016/j.forsciint.2022.111515. Epub 2022 Nov 7.
Bloodstained fabrics found at crime scenes are likely to have had processing treatments, such as dyeing or printing, but the effect of the treatments on bloodstain morphology is not always considered. In order to study the effect of digital printing on bloodstain morphology, drip stains were created from five impact velocities (1.9-5.4 ms) on three different mass per unit areas (88-226 g/m²) of 100% cotton calico which had been digitally printed using reactive dye. Across all three printed fabrics, the bloodstains appeared visually similar, and no correlation was found between the dry bloodstain area and the impact velocity. When comparing the bloodstains on the printed fabric to those which had been created previously on the same fabric in a dyed and not-coloured state, the dry bloodstains on the printed fabric were statistically significantly larger (e.g. for the calico with the lightest mass per unit area, mean dry bloodstain area was 126.6, 64.4 and 44.3 mm² for the printed, dyed and not-coloured fabrics respectively). Examination of the larger bloodstains on the printed calico with the micro computed tomography scanner and scanning electron microscope, suggested that the printing process increased the wettability of the fabric, so the blood could spread more easily on the surface. This allowed the blood to coat the yarns, and wick into them before wicking along the intra-yarn spaces. The results presented in this paper showed that care must be taken when examining bloodstains at crime scenes. Depending on the fabric and the processing of the fabric the size of the blood stains may not increase with impact velocity as wicking may result in a larger bloodstain from a lower velocity. The bloodstain on the penetrated face of the fabric may be larger than on the impacted face and the same fabrics with different processing will produce different blood stain sizes and shapes.
犯罪现场发现的沾血织物可能经过了处理，例如染色或印花，但处理对血痕形态的影响并不总是被考虑到。为了研究数码印花对血痕形态的影响，在三种不同的单位面积质量（88-226g/m²）的 100%纯棉平纹布上，使用活性染料进行数码印花，从五个撞击速度（1.9-5.4ms）制作了滴落血痕。在所有三种印花织物上，血痕在视觉上看起来相似，并且在干燥血痕面积和撞击速度之间没有发现相关性。当将印花织物上的血痕与之前在同一织物上处于染色和非染色状态下制作的血痕进行比较时，印花织物上的干燥血痕在统计学上显著更大（例如，对于单位面积质量最轻的平纹布，印花、染色和非染色织物上的干燥血痕面积分别为 126.6、64.4 和 44.3mm²）。使用微计算机断层扫描和扫描电子显微镜对印花平纹布上较大的血痕进行检查，表明印花过程增加了织物的润湿性，因此血液可以更容易地在表面扩散。这使得血液能够在纱线表面涂覆，并在纱线之间的空间中沿纱线向上渗透。本文介绍的结果表明，在犯罪现场检查血痕时必须小心谨慎。根据织物和织物的处理方式，血痕的大小可能不会随撞击速度的增加而增加，因为渗透可能会导致较低速度下出现更大的血痕。织物穿透面的血痕可能比撞击面的血痕更大，并且具有不同处理方式的相同织物将产生不同的血痕大小和形状。
