LOS ANGELES - (AP) - Lindsay Lohan is under investigation for an alleged misdemeanor battery against a female staffer at a rehab facility where the actress is receiving treatment, authorities said Tuesday.

Riverside County sheriff's Deputy Herlinda Valenzuela saidofficers responded to a Betty Ford Center facility in Palm Deserton Dec. 12 shortly after 1 a.m. for an incident involving Lohan.

Valenzuela says a female staffer reported having a dispute withthe "Mean Girls" star and that she wanted to pursue charges. Noarrests were made and Valenzuela says detectives continue to lookinto the case.

Their results will be presented to Riverside County prosecutors,who will decide whether to file a criminal case, Valenzuela said.

Messages for Lohan's attorney, Shawn Chapman Holley, were notimmediately returned. An e-mail message seeking comment from aBetty Ford spokesman was not immediately returned, although thefacility does not comment on its patients.

Lohan has been receiving treatment at the Betty Ford Center andits facilities, about 120 miles east of Los Angeles, since late September.

A judge overseeing her probation for a 3-year-old drunk drivingcase has required Lohan to remain at the rehab center until Jan. 3.

Los Angeles Superior Court Judge Elden S. Fox has scheduled ahearing on Lohan's progress for Feb. 25. He has said he would bewilling to place her on informal probation and allow her to leaveLos Angeles if she stayed out of trouble until then.

Lohan's stint at Betty Ford is her fifth stay in rehab and hersecond this year. Fox agreed to release her early from treatment atRonald Reagan UCLA Medical Center in late August, but she failed adrug screening within weeks.

Fox opted to send her back to rehab rather than jail, where shewould have been released early due to overcrowding.

The battery investigation was first reported by celebrity newswebsite TMZ.

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