Finding out where someone is incarcerated is often the first and most urgent challenge families face after an arrest or transfer. The Bureau of Prisons maintains a free locator for federal inmates. Every state maintains its own inmate search tool. But knowing which system to search, how to use the locator correctly, and what to do when the search comes up empty requires guidance that most families do not have access to when they need it most. This section covers how to use the BOP inmate locator for federal inmates, how to find state inmates using DOC search tools, what to do when an inmate does not appear in any search system, why someone in transit may be temporarily unfindable, and how InmateAid's free inmate search can help locate a loved one across multiple systems simultaneously. The answers here are written for families searching in real time, often in crisis, who need accurate information fast. See also our sections on Inmate Transfer and General Prison Questions.