All in search of the missing: Citizen participation in missing person searches

In the Netherlands, approximately 30,000 people are reported missing to the police each year. In some cases, these disappearances lead to large-scale search efforts organized by citizens. Such citizen-led searches present both opportunities and risks. Citizens can serve as valuable additional eyes and ears, allowing a larger area to be covered. However, these searches can also destroy traces or evidence, or result in a lack of oversight and coordination. Often, the police have little or no formal authority to prevent or direct citizen search efforts.
The aim of this dissertation is to gain a deeper understanding of how citizens participate in searches for missing persons. It examines how citizens and the police collaborate, what psychological factors motivate citizens to take part in search efforts and investigators to involve them, and how technology can be used to support citizens during searches.
The dissertation consists of five studies. The first is a case study exploring the collaboration between citizens and the police in an actual missing person case. The next two are survey studies that explain citizens’ intentions to participate in searches based on characteristics of the disappearance and on cognitive and affective factors in potential searchers. These studies draw on the Theory of Planned Behavior and Community Engagement Theory. A third survey study examines investigators’ intentions to involve citizens, again from the perspective of the Theory of Planned Behavior. The final study employs a quasi-experimental design to investigate the impact of a specially developed mobile application on a citizen-organized search effort.
Overall, the dissertation demonstrates that citizen participation in missing person searches is not static but dynamic, influenced by contextual, cognitive, and affective factors. It also highlights both the advantages and limitations of technological support for citizen-led searches.