Dec. 21, 2010 -- Lindsay Lohan's clean streak may have met its end.
According to authorities, detectives are investigating Lohan for alleged misdemeanor battery against a female staffer at the Betty Ford Center, the California facility where she's been receiving treatment since September.
Police arrived at a Betty Ford Center facility early Dec. 12 in response to incident involving Lohan, the Riverside County Sheriff's Department said in a statement to ABCNews.com.
"On Dec. 12, 2010 at 1:03 a.m. officers from the Palm Desert Police Department conducted a battery investigation," the statement said. "The incident involved Lindsay Lohan and another female adult who is a staff member. Lohan was reported as a suspect in the investigation. The victim desired prosecution."
"The incident is being investigated as a misdemeanor not committed in the presence of a peace officer," the statement continued. "Therefore, no one was arrested at the scene. The investigation is currently ongoing. Upon completion of the investigation, the reports will be forwarded to the District Attorney's office to determine if charges will be filed in the case."
Lohan's lawyer, Shawn Chapman Holley, declined to comment on the specifics of the case "as we await the completion of the police investigation."
"It should be noted, however, that it was Ms. Lohan who called 911 to request police assistance at the time this incident occurred," Holley said in a statement released late today.
Lohan reported to rehab for the fifth time since 2007 in September after testing positive for cocaine. Earlier this year, she served two prison stints for violating her 2007 DUI probation.
One of the terms of Lohan's probation is to abide by all laws. If she is charged with battery, she could spend another session behind bars.
Until now, rehab seemed to be doing good for the 24-year-old starlet. According to RadarOnline, last week, she celebrated 100 days of sobriety.
While in treatment, Lohan reportedly made ammends with her estranged father, Michael Lohan, with whom she spent Thanksgiving.
The "Mean Girls" actress is reportedly planning to travel to New York to spend Christmas with her mother, Dina Lohan, at the family's Long Island home. It is unclear if the investigation into the Betty Ford incident will affect that trip.