Conrad Murray In Jail With Michael Jackson's Former Brother-In-Law

James DeBarge -- Janet Jackson's ex-husband -- is locked up after being arrested for assault with a deadly weapon and drug charges. DeBarge -- who was the lead singer of the wildly popular band, El DeBarge -- has been placed in Administrative Segregation -- the place where famous inmates with security issues are housed.

Murray has been calling the Ad Segregation unit home since his conviction on manslaughter charges last November.

We're told they occasionally run into each other, most recently last Monday when they were each meeting with their respective lawyers in the visiting room.