The Mean Girls star was moved from the rehab centre to another unit last week (beg13Dec10) to complete her court ordered treatment for violating her probation stemming from a DUI arrest.
But her relocation has been mired in controversy - it emerged on Tuesday (21Dec10) that officers in Palm Desert, California are investigating after a female member of the Betty Ford staff was assaulted during an altercation with Lohan and some pals, according to TMZ.com.
Cops received a call at 1.03am on 12 December (10) for "hand-to-hand battery" - but a source tells the website Lohan was not the perpetrator of the incident.
The troubled actress insists she didn't strike the first blow and merely pushed back at the unnamed member of staff after she was "unfairly" lectured about arriving at the home after her curfew and ordered to take a drug or alcohol test, according to TMZ.
The website claims Lohan yelled, "Take your hands off of me" as the drama escalated, and then "pushed back" against the woman.