Sexual violence against minors is a serious phenomenon, constantly on the increase, and France and Europe have made the fight against these crimes a priority as part of their overall security policy (Directive 2011/93/EU of the European Parliament of 13/12/2011). Police officers generally work in a profession with a high potential for trauma and psychological distress. This is a population with a suicide rate 36% higher than the general population (Senate report 2019). Some specialised police officers and scientific experts from the national forensic science service are on the front line in the daily fight against offences related to sexual violence against minors, which generate specific secondary traumatic stress. Few studies have been carried out on the subject, particularly in France where, to our knowledge, no research has been done on this topic. The STEPS project is innovative in this sense. It aims to evaluate, in the context of their professional activity, the impact of the exposure of specialised police officers and their scientific experts to secondary traumatic stress generated by these criminal acts, and to highlight the factors favouring resilience processes. The aim of the research is to develop a support methodology for accompanying psychologists as well as for managers, in order to detect and effectively strengthen the professional capacities of specialised police forces. This research, resulting from a previous collaboration, integrates a strong partnership between university researchers, police psychologists, specialised police officers and experts from the National Forensic Service.