Lindsay Lohan's father claims she has been battling her drug and drink demons since she was 18.
Michael, 53, has revealed she took cocaine on the set of 'Just My Luck' in 2005 - going against her recent claim she first tried it when she was 21.
He recalled being told of her first overdose and admitted he wanted to "kill" the assistant who gave her the drugs.
He told The Sun on Sunday newspaper: "Lindsay was filming in New Orleans and I got a call saying she had overdosed on cocaine. One of her assistants had given her the drug.
"I was so angry I got a gun from the house and planned to go New Orleans to kill him.
"I couldn't believe that had happened to my daughter. I was just so angry."
Michael also speculated the 'Liz & Dick' star's career could be over if she suffers another "relapse" when her recent 90-day rehab stint is completed.
He added: "If Lindsay does relapse, then I think it will be over for her with Hollywood.
"She takes Adderall and vodka. The combination just turns the brain to mush. People who do that are zonked out."