Toolmark and Materials Laboratory, Division of Identification and Forensic Science, National Headquarters of the Israel Police, Jerusalem, Israel.
J Forensic Sci. 2021 May;66(3):1143-1147. doi: 10.1111/1556-4029.14656. Epub 2020 Dec 17.
Shoeprints are valuable crime scene exhibits because, given a reasonable-quality impression and a suspect shoe, the forensic investigator can correlate the impression with the shoe and pin down a suspect. In similarity to bloody fingerprints, a common practice with bloody shoeprints is that the crime scene investigator photographs the impressions at a 90° angle with a scale, develops them with amido Black, and then photographs again. In most cases, the post-development prints will feature better and more details that are usually sufficient to perform a comparison between the impression found at the crime scene and suspect's shoes. This study examined shoeprints in blood that had been collected in an apartment in northern Israel where two bodies were found. The floor tiles in the apartment had featured a colored design which in the post-development photographs of the shoeprints blended in with the blood on the floor. As a result, the shoeprint impression was partial and small details were masked. In the laboratory, we processed the pre-amido Black photograph in several steps designed to increase contrast. The result of this digital processing was a full shoeprint sufficiently clear to display randomly acquired characteristics of the sole and subsequently establish identification between the impression found at the crime scene and suspect's shoes. When chemical amplification is not sufficient, it is worth exploring other methods before proceeding with the comparison, as it is sometimes still possible to extract information from the same data using alternative methods in order to achieve a conclusive result.
鞋印是有价值的犯罪现场物证，因为只要有一个质量合理的印痕和嫌疑人的鞋子，法庭科学家就能将印痕与鞋子相关联，并锁定嫌疑人。与血迹指纹相似，对于带血迹的鞋印，犯罪现场调查员通常会以 90 度角拍照并附上比例尺，用氨基黑显影，然后再拍照。在大多数情况下，经显影后的鞋印会呈现出更好、更清晰的细节，通常足以对犯罪现场发现的印痕和嫌疑人鞋子进行对比。本研究检查了在以色列北部一所公寓里发现的两具尸体上采集的血迹中的鞋印。公寓里的地砖有彩色图案，在鞋印的显影照片中与地板上的血迹混合在一起。因此，鞋印印痕是局部的，小细节被掩盖了。在实验室里，我们对预氨基黑照片进行了几个步骤的处理，旨在增加对比度。这种数字处理的结果是一个完整的鞋印，足够清晰，可以显示鞋底随机采集的特征，从而确定犯罪现场发现的印痕与嫌疑人鞋子之间的关系。如果化学放大效果不佳，在进行对比之前，值得探索其他方法，因为有时仍然可以通过使用替代方法从相同的数据中提取信息，从而得出确凿的结果。
