Vincent Vinnie the chin Gigante.
. For the better part of 30 years, Gigante feigned insanity in an effort to throw law enforcement off his trail. Dubbed "The Oddfather" and "The Enigma in the Bathrobe" by the press, Gigante often wandered the streets of Greenwich Village in his bathrobe and slippers, mumbling incoherently to himself. He was indicted on federal racketeering charges in 1990, but was determined to be mentally unfit to stand trial. In 1997 he was tried and convicted of racketeering and was given a 12-year sentence. Facing new charges in 2003, he pleaded guilty and admitted that his supposed insanity was an elaborate effort to avoid prosecution.[2] He died while incarcerated in 2005 at the United States Medical Center for Federal Prisoners.
https://en.wikipedia.org/wiki/Vincent_Gigante