Former Deputy U.S. Marshal John Thomas Ambrose was a decorated federal law enforcement officer. However, in 2009 he was convicted of leaking information about a federal witness in the Witness Protection Program

United States Federal Witness Protection Program

The United States Federal Witness Protection Program is a witness protection program administered by the United States Department of Justice and operated by the United States Marshals Service that is designed to protect threatened witnesses before, during, and after a trial.A few states, including...

 (Chicago Outfit hitman Nicholas Calabrese

Nicholas Calabrese

Nicholas W. Calabrese is the first made man ever to testify against the Chicago Outfit. His testimony and cooperation with federal prosecutors helped result in the 2007 murder convictions of mobsters Joseph Lombardo, James Marcello and Frank Calabrese, Sr.- Early life and work outside of the...

) to other members of Chicago organized crime. This represented the first such breach in the history of the program.