Crimes involving weapons have increased in the Netherlands by 24 per cent in the past ten years, while the decrease in reported crimes has stabilised since 2018. Given that crimes with weapons are often complex and are often investigated in a multidisciplinary manner, these trends increase the demands for complex investigations within the Dutch justice system and, therefore, on the Netherlands Forensic Institute (NFI) as well. Here, the department of Human Biological Traces (BiS) examines evidentiary pieces ("Stukken Van Overtuiging', SVOs), such as knives, to find human biological traces, a process that is called the preliminary examination. The preliminary examination is labour-intensive, and with the increasing demands, could benefit from an optimised workflow. However, to identify and improve issues with the workflow, the workflow needs to be known.
In this observational study, all actions during the preliminary examination were observed and measured. These data were used to determine the duration of SVO examinations and laboratory sessions, their parts and their occurrences. The median duration of a laboratory session was 69 minutes, and the median duration of a completed SVO examination was 29 minutes. The duration of an SVO examination is affected by the category of the SVO, the difficulty level of the examination and the research question. Issues of the workflow were categorised as solvable in the short and long term. In the short term, the workflow could be improved by better managing materials and electronic devices. Furthermore, Processing sample kits could be less labour-intensive by adding codes to the sample containers and performing the examination on a work surface with ridges. The availability and reachability of experts may be improved by aligning their availability with the examination. By solving the bottlenecks concerning material management and processing sample kits, respectively, 15.9 and 56.7 hours per year could be won based on the examinations performed in 2024. In the long term, administrative tasks and examinations with the Crime-lite need further research to provide insights to save time.