Los Angeles: Michael Jackson's personal physician Conrad Murray has been charged with "unlawfully, and without malice", killing the pop star last summer.

Murray turned himself in shortly before 4 p.m. Monday at a branch courthouse near Los Angeles International Airport. He pleaded not guilty during a brief hearing before Judge Keith L. Schwartz.

The judge set bail at $75,000, despite arguments from prosecutor David Walgren that Murray is a flight risk. He also refused to suspend Murray's medical licence as a term of his bond, but he did order him not to use any anaesthesia on patients. "I don't want you sedating people," Schwartz told Murray, according to CNN.

Michael Jackson's family, including his parents, three of his brothers and one sister, filled the first two rows of the small courtroom.

The involuntary manslaughter charge means that Murray caused Jackson's death by acting "without due caution and circumspection". If convicted, Murray would face a maximum four-year prison sentence, according to prosecutors.

Murray, a cardiologist, was hired as Jackson's personal physician last spring as the singer prepared for comeback concerts in London.

The doctor told Los Angeles police that he was with Jackson at his $100,000-a-month rented Holmby Hills mansion through the early morning hours of June 25, 2009, in an effort to help the pop star fall asleep, according to a police affidavit.

He administered sleep aids, and after Jackson finally began sleeping in the late morning hours, Murray said, he left the bedroom for "about two minutes maximum", the affidavit says. "Upon his return, Murray noticed that Jackson was no longer breathing," it says.

The doctor stayed with Jackson as an ambulance rushed him to UCLA Medical Centre. Efforts at CPR proved fruitless, and Jackson was pronounced dead at 2.26 p.m.

The Los Angeles County coroner ruled Jackson's death a homicide, resulting from a combination of drugs, primarily Propofol and Lorazepam.