Craig Titus and his wife Kelly Ryan were two of the biggest stars of the body building world. The duo - he, a Mr. Olympia competitor and she, a fitness champion - won numerous competitions and graced magazine covers. Titus even trained Motley Crue lead singer, Vince Neil, who admits to 48 Hours Mystery that Titus used steroids and injected him with them. And steroids were not Titus' only drug of choice. These Las Vegas hard bodies were also hard partiers, known for using illegal drugs and pain killers. But all that changed on Dec. 14, 2005, when the charred corpse of a young woman was discovered in Ryan's burned out car on a Las Vegas desert road. The unrecognizable body was initially thought to be Ryan, but authorities were stunned when they arrived to the couple's house only to be greeted by her at the door. The body was that of their live-in assistant Melissa James. And soon police pieced together the web of fame, sex, drugs and jealousy that ended in this brutal murder, a gruesome cover up and the downfall of a fitness powerhouse. Now, in a 48 Hours Mystery exclusive, family, friends, detectives and witnesses each shed light on this shocking story. And, for the first time, shamed body builder Craig Titus tells his side of what happened the night James died, insisting to 48 Hours Mystery that is wasn't murder. "She OD'd. She'd been shooting drugs for days…I never intended to kill Melissa James, murder Melissa James." Correspondent Peter Van Sant reports on the case.