Department of Trace Examination, Criminal Investigation Police University of China, Shenyang, China.
Department of Trace Examination, Criminal Investigation Police University of China, Shenyang, China.
Forensic Sci Int. 2020 Dec;317:110514. doi: 10.1016/j.forsciint.2020.110514. Epub 2020 Sep 18.
The three-dimensional (3D) printed key is a key that can be manufactured from its virtual model by means of a 3D printer. This research focuses on the picking feasibilities and traces that can be observed and exploited from a forensic point of view after the picking of such type of keys. In this paper, 40 printed keys were manufactured using three different polymer materials (white resin, white nylon powder and black ABS). All the experiments were carried out under controlled conditions to allow the collections of data and traces produced by the picking. Of the 40 prints, only 38 picked the locks and the total picking ratio was 95 percent, meaning that a 3D printed key using polymer materials can be used to pick a lock. Elements of lock - pins and keyways - appeared to carry polymer materials (flakes or pieces) transferred from the prints during picking process. Additional, characteristic marks of a 3D printed key on the surface of pins was identical to those of an original key, but not similar to those of other picking tools. Indeed, this method could not create more marks on the bits of an original key while striations were left by the picking method using a duplicated key. Besides, FT-IR was a useful method of analyzing the type of polymer material used. When receiving original keys and a lock suspected to be picked in a crime scene, the toolmark examiners can quickly determine whether or not the lock was picked by a 3D printed key based on the examination results of these traces.
3D 打印钥匙是一种可以通过 3D 打印机根据其虚拟模型制造的钥匙。本研究侧重于从法医角度观察和利用此类钥匙被撬后的可识别特征和痕迹。在本文中，使用三种不同的聚合物材料（白色树脂、白色尼龙粉末和黑色 ABS）制造了 40 个打印钥匙。所有实验均在受控条件下进行，以允许收集撬锁过程中产生的数据和痕迹。在 40 个打印钥匙中，只有 38 个能够打开锁，总开锁率为 95%，这意味着使用聚合物材料的 3D 打印钥匙可以用来开锁。锁的弹子和键槽等元素似乎携带了在开锁过程中从打印品上转移过来的聚合物材料（薄片或碎片）。此外，打印钥匙表面上的特征痕迹与原始钥匙相同，但与其他开锁工具不同。实际上，这种方法在使用复制钥匙进行开锁时不会在原始钥匙的齿上留下更多痕迹，而只会留下划痕。此外，FT-IR 是分析所用聚合物材料类型的有用方法。当收到犯罪现场中涉嫌被撬的原始钥匙和锁时，工具痕迹检验员可以根据这些痕迹的检验结果，快速判断锁是否被 3D 打印钥匙撬开。
