Lindsay Lohan "Demure and Quiet" as She Arrived at Jail

Credit: LASD

Lindsay Lohan was booked at Los Angeles County's Century Regional Detention Center at 10:35 a.m. Friday, L.A. Sheriff's spokesman Steve Whitmore tells

He says she was "very cooperative, very demure and quiet. She's doing everything that is asked of her."

Just like her previous stints in the slammer, she will be held away from other inmates in a 12x9 cell until her next probation violation hearing, set for Oct. 22, he says.

Asked if the actress, 24, could be released early, Whitmore tells Us, "The only way this inmate would be released is if the judge issues another order."

The actress - who was thrown back behind bars because she failed at least one random drug test - served nearly two weeks in jail in July for violating terms of her three-year-old DUI case. She then went to rehab, but was released early Aug. 24.