(AP)

Prosecutors on Monday charged Michael Jackson's personal physician with involuntary manslaughter in connection with administering a combination of surgical anesthetic and sedatives blamed in the music legend's death last summer.

The complaint filed by the Los Angeles County district attorney's office alleges that Dr. Conrad Murray "did unlawfully and without malice kill Michael Joseph Jackson, a human being, in the commission of an unlawful act not amounting to a felony; and in the commission of a lawful act which might have produced death, in an unlawful manner, and without due caution and circumspection."

[Updated at 2:10 p.m.: Murray arrived in court and pleaded not guilty. Bail was set at $75,000.] Jackson's parents, Kathryn and Joe, as well as some of his brothers arrived at the courthouse shortly after the charge was filed.

In a news release, the district attorney's office said Deputy Dist. Atty. David Walgren, a prosecutor in the major crimes division, would try the case. Walgren is also handling the attempt to extradite movie director Roman Polanski to face sentencing in a three-decade-old child-sex case.

The release credited the LAPD and the county coroner's office for building the case against Murray. "Both agencies worked diligently and exhaustively to collect the evidence leading to the filing of the case," the statement said.

[Updated at 1 p.m.: Murray walked into the courthouse at 12:55 p.m. to shouts of "murderer" from a handful of Jackson fans whose presence was dwarfed by an international contingent of media who began camping out at the courthouse last week. He is scheduled to be arraigned at 1:30 p.m.]

Brian Oxman, Joe Jackson's attorney, said some family members were disappointed that the physician was charged only with involuntary manslaughter.

The criminal case comes after a seven-month investigation that stretched from the master bedroom of Jackson's Holmby Hills mansion to the heart clinic Murray ran in a poor neighborhood of Houston. The focus, however, rarely left Murray.

Within weeks of Jackson's death, detectives described the doctor as a manslaughter suspect in court papers that said he admitted leaving the singer alone and under the influence of propofol -- a powerful anesthetic used to render surgical patients unconscious -- in a bedroom of the sprawling home.

The coroner's office ruled Jackson's death a homicide and said the cause was "acute propofol intoxication" in conjunction with the effect of other sedatives Murray acknowledged providing.

Despite the almost immediate focus on Murray -- authorities first questioned him in the hospital where doctors were working in vain to revive Jackson -- the multi-agency probe that included federal and local investigators progressed slowly, and the doctor was not formally accused of wrongdoing until the district attorney's office filed its complaint.

Involuntary manslaughter is the least serious homicide charge available to prosecutors, its maximum punishment of four years in prison far less than the life sentence for murder or the 11 years for voluntary manslaughter. The charge, which applies to an unlawful killing committed without malice or intent to kill, turns on Murray's possible negligence in allegedly giving Jackson propofol for an unapproved purpose -- the treatment of insomnia -- and outside of the normal operating room setting.

The drug, one of the most widely used general anesthetics in the nation, is so dangerous that the U.S. Food and Drug Administration says only those trained in anesthesia should administer it.

Murray told police that he had been giving Jackson nightly intravenous doses of propofol for six weeks, about the time he began working for the performer, according to police affidavits filed in court. Murray, who was in debt and behind on child-support payments, earned $150,000 a month treating Jackson and closed practices he operated in Las Vegas, where he lived, and Houston to join the performer in Los Angeles for rehearsals.

According to the affidavits, Jackson told the physician that for years other doctors had treated his chronic insomnia with doses of propofol, a white liquid the singer called "milk."

Murray eventually became concerned that the singer was addicted and tried to wean him off the anesthetic, according to the affidavits. On the day Jackson died, Murray tried to get the performer to sleep using Valium and, later, two other sedatives, according to the affidavits. But Jackson remained awake for 10 hours, demanding propofol.

According to the affidavits, Murray said he relented and sat next to Jackson's bed as the propofol took effect. He told police he left for two minutes to use the restroom, and cellphone records indicate he also talked on the phone for 45 minutes, according to the affidavits. When he returned, Jackson was not breathing.

Through his attorney, Murray has maintained his innocence and said he did nothing that should have caused Jackson's death. In his only public comment -- a one-minute video released in August through his lawyer -- a somber-looking Murray expressed confidence that he would be exonerated. "I told the truth, and I have faith the truth will prevail," he said.