"The judicial process may have been improperly circumvented in this case," said City Attorney Rocky Delgadillo. "This explanation is puzzling. Los Angeles County jail medical facilities are well-equipped to deal with medical situations involving inmates."
Sheriff Lee Baca released Hilton early Thursday to serve 40 days at her Hollywood Hills home after she served three days of what was expected to be a 23-day stay for violating probation in a reckless driving case.
While Baca's spokesman said the judge who sentenced her had been consulted, he didn't mention that Superior Court Judge Michael T. Sauer objected to her release. When Sauer sentenced her last month he specifically said she could not do her time at home.
"He did not agree to the terms of release that the sheriff proposed," said Superior Court spokesman Allan Parachini.
But Sheriff's Department spokesman Steve Whitmore noted it's not unusual for inmates to finish sentences under home confinement.
Activists and former inmates are speaking out against Hilton's transfer.
"If that had been me and I had a medical condition, they would have sent me to county medical. They have a facility in here, and then I would have been right back in my cell," released inmate LaToya Wilson told CBS News correspondent Bill Whitaker.
"Paris Hilton got a free get out of jail card today by manipulating and using her celebrity status to get out of jail," said civil rights activist Najee Ali.
Even Al Sharpton is on his way to L.A. to protest celebrity injustice in front of Hilton's house.
In the last five years in LA County, more than 200,000 inmates have been released early. Because of prison overcrowding, the vast majority serve less than 10 percent of their sentences. But a quick medical release like Paris' is rare, Whitaker reports.
Hilton was sent home with an electronic monitoring ankle bracelet and must remain there for 40 days, according to sheriff's spokesman Steve Whitmore.
Whitmore says Hilton left the Century Regional Detention Facility in Lynwood just after midnight.
She checked into the facility just after 11:30 p.m. Sunday to serve 23 days, down from the 45 days she was originally sentenced to.
Whitmore says Hilton's sentence will return to a 45-day term, with five days' credit for time served.
Hilton will be under the supervision of the L.A. County probation department, Whitmore said.
Photos: Paris In Stripes
Whitmore also said a medical issue was involved, but could not elaborate because of privacy issues. Overcrowding and a reported staph infection at the facility did not play a part in her reassignment, Whitmore said.
TMZ.com first reported that Hilton was released from jail early.
Hilton surrendered to authorities on Sunday with little fanfare after a surprise appearance earlier that day at the MTV Movie Awards, where she worked the red carpet in a strapless designer gown.
Hilton was housed in the "special needs" unit of the 13-year-old jail, separate from most of its 2,200 inmates. The unit contains 12 two-person cells reserved for police officers, public officials, celebrities and other high-profile inmates. She didn't have a cellmate.
After her first night in jail, Hilton's lawyer, Richard A. Hutton, said she was doing well under the circumstances.
"She's using this time to reflect on her life, to see what she can do to make the world better and hopefully, in my opinion, to change the attitudes that exist about her among many people," Hutton said after visiting Hilton.
When she was sentenced May 4, Sauer ruled that she would not be allowed any work release, furloughs or use of an alternative jail or electronic monitoring in lieu of jail.
Sheriff's officials had said she would serve about 23 days of her 45-day sentence behind bars because of state rules allowing shorter sentences for good behavior.
The star of "The Simple Life" reality TV show pleaded no contest to a reckless-driving charge in January and was sentenced to 36 months' probation. When she was later pulled over by the California Highway Patrol, Hilton was told that she was driving on a suspended license and signed a document acknowledging she was not to drive. She was then pulled over by sheriff's deputies on Feb. 27 and charged with violating probation.