This is a quantitative study using descriptive statistics methods to analyze how deaths from unknown causes in the Brazilian prison system from 2014 to 2021 show an ongoing death policy (necropolitics). The research started with the gathering and organization of official data on mortality rates in Brazilian prison institutions. After tracing the scenario of deaths of unknown cause in the prison population, we examined data from the Mortality Information System (SIM) of DATASUS, which counts and classifies deaths in Brazil over the years. Finally, we analyzed the behavior of data from time series of deaths of unknown cause in terms of increase or decrease. The data analyzed showed that deaths due to unknown causes in Brazilian prisons represented, on average, 10% of the deaths that occurred in the period considered. Comparing the results with data on deaths from external causes in the population shows that the conditions of deprivation of liberty associated with a necropolitical context enhance the lack of commitment to public care policies for citizens under the guardianship of the state.