Credit: Jean Baptiste Lacroix/WireImage

Lindsay Lohan's in trouble again.

With just two weeks left to go at the Betty Ford Center, the 24-year-old is the subject of a brand-new police investigation.

A female staffer at the treatment facility is accusing Lohan of attacking her; according to reports, Lohan flew off the handle when the staffer asked her to submit to a drug and alcohol test.

"Lohan was reported as the suspect in the investigation and the victim desired prosecution," a spokesperson for the Palm Desert Police Department told E! News.

The alleged incident is a misdemeanor, added the spokesperson, and the investigation is "ongoing."

Per court order, Lohan was scheduled to leave the rehab Jan. 3 -- but L.A. Superior Court Judge Elden S. Fox warned he'd send Lohan to jail for up to six months if she got into trouble.

She was originally sent to Betty Ford as punishment for violating her probation stemming from a 2007 DUI.