What does us marshall detainer means?

A U.S. Marshal detainer is a request or order issued by a federal law enforcement agency, specifically the U.S. Marshals Service, to hold a person in custody. This typically occurs when an individual is wanted for federal charges or has outstanding warrants. The detainer ensures that the individual is not released from state or local custody until federal authorities can take action on the case. It is often used to facilitate the transfer of individuals to federal jurisdiction for prosecution.