Study on traces left on a mechanical lock picked by a 3D printed key in toolmarks examination.

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.

The Identification of a Steel Mold's Marks on Fake Drug Bottles.

Plastic bottles are commonly encountered in drug cases where they are used as packaging materials and produced with polymers. However, to the best of our knowledge, systematic studies on the evidential values of medicine bottles have not been carried out. Therefore, it is difficult practically to determine if it is possible to identify whether the plastic bottles are manufactured with the same steel mold by comparing the manufacturing marks on plastic bottles. This paper reports the successful attempt of the authors in establishing a definite relationship between three different medicine bottles with a steel mold recovered from suspects. Fourier transform infrared spectroscopy (FT-IR) was used to characterize the chemical composition of submitted medicine bottles, and then some physical characteristics (viz., total length, length, and diameter of different parts) and the manufactured marks on these bottles were examined. The results showed that the linkage of the medicine bottles to a steel mold was successfully established using the similarities in physical characteristics and manufacturing marks. In the process, the FT-IR was only complementary in the identification process. The individual characteristics of plastic medicine bottles included the imperfections and striated impressions that were produced by the grinding patterns on the inner surface of a steel mold.