toolmarks

Toolmarks are, along with shoe marks and DNA marks, one of the most common types of marks in Germany. The number of fingerprints decreases in the same proportion as the number of glove marks increases. All other types of traces occur only in a crime-specific manner. If the police investigator focuses toolmarks on burglaries, there are over 75% pure lever marks on doors and windows. This clearly shows the weighting and thus the investigative approaches. Interestingly, only three German state criminal investigation offices maintain collections with leverage (Bremen, Schleswig-Holstein and Rhineland-Palatinate). The small state of Bremen is at the forefront here and has carried out various black box tests by the forensic engineers and criminal inspectors Matthias Thoden and Matthias Braune. For this reason, the focus is mainly on tool impression marks, together with a holistic securing of the lever channel. Sliding marks that are still mainly used in other crime techniques play a minor role in Bremen. The surfaces of the tools (e.g. sandblasted) and the specific tool geometry are reflected in a lever track. Due to improved optics, the individual impacts of the grains in the track can now be identified. The materials in which the traces are located do not pose any obstacles for the experts. It can be wood, metal, plastic, bone and cartilage tissue. The training covers all materials. The field of toolmarks basically covers all engineering faculties. At least 10% of all inspection orders represent unknown problems that need to be researched by the engineers. The difficulty usually lies in creating a suitable comparison track that is suitable for a comparison between the track of the crime scene and the comparison track, so that the court can follow the expert's expertise. In order to be able to understand the origin of the trace, the images of the crime scene are consulted in any case, since important insights can already be gathered here. The pictorial trace comparisons are usually shown in the report. Under the leadership of the forensic expert Rainer Schubert from the State Criminal Police Office in Saxony, toolmark comparisons are currently being carried out using 3D detection technology and 3D printing technology. The goal is to make hasty comparisons for matching toolmarks and fitting pieces understandable for the court. Toolmarks on human bones as well as on human cartilage also belong to the activities of German experts in the field of technical formtracks. The State Criminal Police Offices of North Rhine-Westphalia (by the forensic engineer Matthias Weber) and Bremen have carried out a number of black box tests and developed methods to enable them to carry out examinations professionally. A toolmark inspection takes much more time than a chemical determination of a substance. There is no machine that can perform the forensic analysis. The expert for technical formtracks must carry out the analysis with his experience and specialist knowledge.

visualization of removed embossed marks

Objects are marked with numbers, letters or other signs by the manufacturer or the owner for various reasons. The marking can be created by e.g. hammering in with a punch (embossing), mechanical engraving, electrical engraving, laser process, scratch embossing or hot stamping. . The original markings can be manipulated by different methods and thus made illegible and / or falsified, by e.g.: • Grind and roll over with new characters • thermal influence (melting) • Apply material (cold: application of paint, filler, plastic; warm: soldering, welding) • Attaching another "original identification (covering: e.g. with a piece of sheet metal that contains an incorrect marking; cutting out: the original number plate is removed and new (or from another vehicle) is welded into it The visualization of removed license plates is based on the energy introduced by the respective marking process. Part of this energy is stored in the structure of metallic materials in the form of lattice defects, and in plastics by rearranging molecular chains. The physical and chemical properties in the area affected by the marking differ from the undisturbed base material. This fact is used to make marks visible in metals and plastics. In Germany, the following examination methods are used to make embossings visible in metals and plastics: Metals • relief polishing • magnetic process • chemical etching • electrolytic etching • heat treatment Plastics • relief polishing • welling process • heat treatment The chemicals and impression media must be checked for their best-before date before use. Non-destructive testing methods are used first if possible. The Germany-wide specialists for visualization is located at the Federal Criminal Police Office (BKA), the forensic scientist and engineer Bert Weimar and the forensic scientist and engineer Matthias Weber from North Rhine-Westphalia. .

reconstruction of burglary or other crimes

The reconstruction of a crime is not only an essential part of criminal proceedings in the event of break-ins, it is also often necessary in the case of capital offenses (murder, sexual offenses, robbery). This makes it possible to clarify how an act took place, taking into account the position of the tracks, whether it actually took place according to the information provided by the person concerned and what experience the burglar had gained. In addition, a reconstruction can provide important clues of incorrect work when installing doors and windows. In some state criminal investigation offices, the experts drive to the crime scene and carry out such reconstructions. Unfortunately, there are many self-appointed experts in Germany who work for insurance companies and prepare highly erroneous reports for criminal and civil proceedings. These false reports must be corrected in the course of the legal proceedings by the forensic experts of the State Criminal Police Offices by means of a top report. In Germany, these unsuitable appraisers also include experts who are designated by the chambers of crafts as 'publicly appointed'. Due to insufficient training, there is a lack of the necessary specialist competence to be able to carry out extensive reconstructions. This has become a major problem in Germany since the judges make incorrect judgements based on the incorrect expert opinions.

interesting facts...

Hardly any locks, doors or windows can be opened without tools. If someone is using a tool, traces of this tool are almost always found.. With well-structured toolmark collections, connections between several crime scenes can be made quickly. However, the prerequisite for this is that you have a good classification system. Perpetrators do not only use commercially available tools. They often build a tool that can be used for a specific purpose. The traces that are created with this tool are not always classifiable by the expert. But when securing this special tool, a specific assignment is possible and can be found quickly in a toolmark collection. In order to be able to make a comparison between the toolmark from the crime scene and the comparison track generated in the institute with the presumed tool, the assessor needs a so-called 'comparison microscope'. With this microscope, the assessor can view two objects or samples simultaneously and thus compare them. In 2001, Leica developed a comparative microscope for the technical formtracks together with the State Criminal Police Office of Bremen. It is the Leica FSC. Due to the increased requirements for toolmark comparisons, the State Criminal Police Office of Bremen is working on a comparison microscope with the Keyence VHX-7100. Another alternative is the Czech ToolScan system from Laboratory Imaging. It lags behind Keyence's products in terms of resolution, but brings a quick comparison with simple toolmarks (e.g. traces of roller wrenches in profile cylinders). The disadvantage of toolmarks is that they cannot directly identify a perpetrator. A perpetrator relationship must always be proven. The following etchants have been used in Germany to date: Ferrous metals - etchant by Oberhofer - etchant by Meyer-Eichholz - etchant by Fry - etchant by Wazau - etchant by Adler - etchant by Nital Aluminum materials - etchant Alu 1 (hydrochloric acid) - etchant Alu 2 (sodium hydroxide solution) - etching agent Alu 3 (hydrochloric acid-aqua) - etching agent Alu 4 (phosphoric acid aqua) Electrolytic etching - etchant Elo 1 (H2O, HNO3, NH4Cl) - etchant Elo 2 (H2O, oxalic acid for stainless steels) Different swelling agents are used for plastics in Germany: - acetone (PVC) - petrol (ABS, PPh) - restoplas (PA, PPh, PE-HD)