Mariah Carey's brother fears her drinking will kill her and claims he has never seen her sober.
The 'Hero' hitmaker's sibling Morgan - who hasn't directly spoken to the singer in two years - fears the star is unable to care for her four-year-old twins Moroccan and Monroe because he believes she is trying to numb her problems with wine and champagne.
Alleging she has been a heavy drinker since suffering from mental health problems in 2001, Morgan said: "Mariah was drinking through her pregnancy -- even while she was nursing.
"I can't say that I have ever been around her when she was sober, and that's very scary."
Morgan also claimed his 45-year-old sister takes a daily cocktail of medications including Zyprexa, Ativan and Depakote, and fears she will "die like Whitney Houston".
He added to the National Enquirer magazine: "She does not have a support system, and she is not mentally capable."
Morgan is concerned the 'Without You' singer has "pushed away the only people who've been trustworthy" and will blame her entourage if anything does happen to her.
He said: "If my sister turns up dead ... I'm not going to look the other way! Anyone who's filling her glass is jeopardising her life!"
Mariah's brother also branded her estranged husband Nick Cannon a "crock of s**t" who wasn't good for his sister and was only interested in money.
He said: "Nick listened to people who said, 'Get with Mariah, she thinks you're cute, have kids and ride it to the bank.' Nick was there for the cash from day one. He doesn't give a damn about Mariah.
"Nick took tremendous advantage of her and continues to do so."