Brian Greenwald is a jewel thief who admitted to laundering money on behalf of Gambino associate Joe Watts when he was caught for his involvement in a botched jewel heist in '08. (botched because the thiefs were unbable to offload the gemstones) As part of his plea deal, he testified against Joe the German & was sentenced to 27 months. With his bid coming to a close, he has decided to remain in prison while his WitSec information is processed.

Why? As he told Manhattan federal court Judge Harold Baer;
"...I testified against a certain individual who is life-threatening for me...I've had to watch my back for organized-crime retaliation. I've learned recently they are trying to find out where I am. I've been in four separate jails and spent the last seven months in segregation,"

http://www.nypost.com/p/news/local/manhattan/mob_rat_keep_me_in_prison_oi1RpHyG8U3IdYn0zP09NO