the figure of the suspicious ethnographer tends to be a constant in early fieldwork. based on an anthropological experience in police schools, the aim of this article is to dismantle that construction of distrust, espionage and intransigence with which the subjects face both the ethnographer and his study, understanding it as an instance used to undermine his pretended authority and to negotiate the boundaries of the research. to declare this involves sustaining that the role of the research is not under the pure control of the ethnographer. this role, on the contrary, is highly permeable to the actions of the subjects in the field. blurred, disputed and confronted, the role of the ethnographer thus turns out, by virtue of this conflict of skills and competences, to be a sort of cooperative enterprise.