Michael Lohan says his famous daughter is hooked on alcohol and OxyContin

Lindsay Lohan's estranged father says she suffers from multiple addictions, including alcohol and the painkiller OxyContin, the Web site E! Online reported.

The 20-year-old actress checked into rehab Monday following a weekend that included crashing her Mercedes, being arrested for suspicion of driving under the influence and being photographed slumped in the passenger seat of a friend's car. This is her second rehab stint this year.

"I spoke to the people treating Lindsay, because I wanted to make sure she was getting the right care," Michael Lohan told E! Online. "And I'm satisfied they are doing the right thing for her, helping her detox from the painkillers and things. That's a very important step."

Lindsay Lohan's publicist, Leslie Sloane Zelnik, did not immediately return an after-hours call and e-mail from The Associated Press on Wednesday.

Michael Lohan was released from a New York state prison in March after serving almost two years for driving while intoxicated and other charges. He said he is studying to become a drug-rehab counselor with the faith-based organization Teen Challenge.

Before entering rehab, the actress was scheduled to start work this week on "Poor Things," a comedy featuring Shirley MacLaine, who is also a producer on the movie. MacLaine and co-producer Rob Hickman said in a statement Wednesday that Lohan still wants to work on the project.

"We are trying to rearrange the shooting schedule to facilitate her working at the end of the shoot to coincide with the completion of her rehabilitation," the statement said.

In other events swirling around Lohan, authorities who have been conducting undercover operations at trendy celebrity watering holes in recent weeks are seeking to find out if she was served alcohol before her weekend car crash. Lohan is still more than a month away from turning 21, the legal drinking age in the U.S.

California Department of Alcoholic Beverage Control investigators also want to know if Lohan or others were served after hours, agency spokesman John Carr said.

Videos show Lohan leaving Hollywood's Les Deux club at 3:30 a.m.

Alcohol cannot be served in California after 2 a.m.

The Department of Alcoholic Beverage Control told the Beverly Hills Police Department it wants to review witness reports and other evidence to determine if a formal investigation is warranted, Carr said.

Les Deux owner Lonnie Moore said in a statement that Lohan stayed late having dinner and waiting for friends, and was not drinking.