Lindsay Lohan might be in trouble with a judge again Thursday if she fails to prove to the Los Angeles County Superior Court that she has enrolled in rehab.
A hearing is scheduled Thursday morning, but Lohan is not required to attend.
A source in the Los Angeles city attorney's office said they had not yet heard anything about whether Lohan had entered a rehabilitation facility to serve her 90-day sentence.
She initially said she wanted to go to rehab in New York.
A Los Angeles judge sentenced the actress to serve 90 days in a drug rehabilitation facility, directed her not to leave the facility for any reason and said there would be no passes of any kind that allow her to leave the grounds.
The facility does not have to be locked, but the judge made it clear she would violate her probation if she left at any time. Officials will be monitoring her progress.
Her father, Michael Lohan, told CNN that she boarded a flight to Los Angeles late Wednesday to sort out where she will get her treatment.
He said her attorney had arranged for the actress to check into Morningside Recovery in Newport Beach, but it hadn't been approved by prosecutors.
"Lindsay had no idea that Morningside wasn't approved," Michael Lohan told CNN. "It's not her fault. This poor kid was a mess before she left."
The "Mean Girls" star avoided jail in a last-minute deal by pleading no contest to misdemeanor reckless driving and providing false information to police. A charge of willfully resisting, obstructing or delaying an officer was dismissed. In addition to spending 90 days in rehab, she must also spend 18 months in psychotherapy and serve 30 days of community service.
In pleading no contest, Lohan admitted she had violated her probation in a 2011 shoplifting case.