Oversight of police is indispensable in a democratic society. Police officers possess far-reaching powers that allow them, among other things, to use legitimate force and deprive people of their freedom. Since this can have a particular impact on the personal integrity of citizens, it is necessary to ensure that these powers are used within the legal framework. In order to exercise such oversight, a number of bodies have been set up in Belgium: the Vast Comité van Toezicht op de politiediensten and the Algemene Inspectie van de federale politie en van de lokale politie as external bodies, and the Diensten Intern Toezicht as internal supervisory bodies. This contribution focuses mainly on the latter actor. The Diensten Intern Toezicht remain underexposed in academic research on the one hand, despite their interesting position, and provide little insight into their activities themselves on the other hand. As such, despite their front-line function in the supervision of local police, the Diensten Intern Toezicht are an actor with little visibility. Internal supervision at the federal level is possibly even more of a blind spot. In this exploratory article, therefore, we discuss the results of an online survey regarding the Diensten Intern Toezicht and two group interviews with federal police officers to map the functioning of internal oversight at the federal level. With regard to the latter, we focus mainly on the Bureau voor integriteitsbevordering en -bewaking and the Dienst Toezicht op de Interne Werking en Kwaliteit.