Denunciations are prevalent in authoritarian regimes. Citizens turn against each other to report suspicious behaviour to the police state. But citizens may also have incentives to spread false information about their peers. In this context, can denunciations ever be informative? And, if so, what factors impede or facilitate the informativeness of denunciations? We design a formal model of denunciations in a large society. We show that denunciations are informative despite the certainty that some denunciations are false. \red{Future works will} highlight the complementarities between using informants and relying on denunciations for the secret police. We will also study how the regime can encourage denunciations and what it gains and potentially loses from incentivizing people to inform on one another.