Lindsay Lohan Lindsay Lohan

A probation report says Lindsay Lohan tested positive for alcohol while she was in rehab and afterward, according to People.

Lohan drank the night that she snuck out of the Betty Ford Clinic and was accused of battery against a staff member at the rehab center, the report says. That charge was dropped later because of insufficient evidence. She also failed a random alcohol test in February, after she had already checked out of rehab. Lohan's court-ordered stint at Betty Ford lasted from Sept. 27 to Jan. 3.

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Additionally, Lohan's probation officer "believes that substance abuse is the root of the defendant's problems," according to the report.

Another tidbit in the probation report: Lohan — who allegedly stole a $2,500 necklace from a store in Venice, Calif., in January — "has been suspected of similar conduct in other jewelry stores." No charges ever were filed in those instances, however.

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Last month, Lohan was slapped with a 120-day jail sentence and 480 hours of community service for violating her probation as a result of the necklace snafu. She is expected to serve a reduced sentence due to jail overcrowding.

Additionally, she pleaded no contest Wednesday to a misdemeanor theft charge and was sentenced to three years' probation and shoplifting counseling.