LATEST: D-12 rapper PROOF was reportedly murdered after he turned a heated argument inside a Detroit, Michigan, nightspot into a violent struggle. The details emerged as bouncer MARIO ETHERIDGE, a main suspect in the case, turned himself in to police yesterday (12APR06) afternoon. It is believed Etheridge shot Eminem's best man in retaliation, after he opened fire on fellow doorman KEITH BENDER at the CCC nightclub in the early hours of Tuesday morning (11APR06). A source tells, "Proof knocked (Bender) down and stood over him with gun in hand. "Proof shot first. The bouncer on the ground didn't shoot Proof another bouncer did. Proof was shot 4 times. Twice in the head and twice in the chest/stomach area. "(Bender) is on life support and not expected to live at all." Police reveal two guns were probably used in the altercation, and believe Proof - real name DESHAUN HOLTON - was licensed to carry his firearm.