Police want Lindsay Lohan charged with battery over her skirmish with a Betty Ford Centre rehab technician.
A two-week investigation shows the troubled 24-year-old actress broke her probation during the altercation last month and details will be sent to the Los Angeles County Probation Department this week, Riverside sheriff's sergeant Joe Borja said.
A Beverly Hills judge has said Lohan will be jailed if she violates probation.
Investigators expect to take their case to the Riverside County district attorney's office this week for possible prosecution, Sgt Borja said.
Lohan returned to the Rancho Mirage drug dependency centre on December 12 after curfew and refused rehab worker Dawn Holland's request to take a breathalyser test, according to investigators.
Lohan is accused of pushing Ms Holland, who then called police, and Lohan ripped the phone away and injured Ms Holland's wrist.
The actress has been receiving treatment at the clinic, about 120 miles east of Los Angeles, since late September. Los Angeles Superior Court judge Elden Fox, who has overseen Lohan's probation for her three-year-old drink-driving case, required Lohan to remain at the rehab centre until Monday.
John Hall, spokesman for the Riverside County district attorney's office, said his office expected to receive investigators' findings this week. If Lohan is prosecuted in Riverside County, the Los Angeles County Probation Department would be notified, he said.
"The important, yet limited, investigatory role of the police to gather facts and collect evidence is well established," Shawn Chapman Holley, Lohan's lawyer, said.
"The fact that (police) went outside this limited role to issue a press statement expressing its opinion about what should happen in Ms Lohan's case is highly unusual and deeply troubling."
The actress is due back in court on February 25 in Beverly Hills for a hearing at which Judge Fox is expected to address her probation and the Betty Ford incident.
Lohan was due to be released from Betty Ford on Monday, but there were conflicting reports about when she left rehab.
RadarOnline posted a mobile phone video of what appeared to be Lohan with her father Michael, greeting her Freaky Friday co-star Jamie Lee Curtis. The celebrity site said the video was taken at the Four Seasons hotel in Los Angeles.
Lohan herself remained silent on Twitter and her lawyer did not specify when the actress was released.
A spokesman for the Betty Ford Centre said it did not comment on its patients.