Michael Jackson's doctor returns to court in April to find out the date for the next major step in the case _ a proceeding that will reveal for the first time the evidence the prosecution believes will show his "gross negligence" was the direct cause of the pop star's death.

Dr. Conrad Murray pleaded not guilty Monday to a charge of involuntary manslaughter and a judge released him on $75,000 bail.

Superior Court Judge Keith Schwartz ordered Murray to turn in his passport and said he could travel within the U.S., but not to any foreign country. The prosecutor had suggested he might flee to his native Grenada or to Trinidad where he has a child.

Murray was ordered to return April 5 to have another date set for his preliminary hearing. That proceeding, a virtual minitrial, will disclose the evidence prosecutors maintain will demonstrate Murray's "gross negligence."

Murray is accused of giving Jackson a fatal dose of an anesthetic to help him sleep. Jackson died June 25. If convicted, the doctor could face up to four years in prison.

Schwartz told Murray he was restricting his practice of medicine, barring him from using any anesthetic agent, specifically the drug propofol that a coroner's report found was the cause of Jackson's death with other drugs as contributing factors.

"I don't want you sedating people," the judge said.

Immediately after the hearing, LaToya Jackson issued a statement saying she believed her brother had been murdered and that others besides Murray were involved in his death.

"I will continue to fight until all of the proper individuals are brought forth and justice is served," LaToya said. She was in court along with siblings including Jermaine, Tito, Jackie and Randy.

Her father, Joe Jackson, expressed the same views Monday night in an interview on "Larry King Live" and claimed that his son believed he was going to be murdered. He did not elaborate.

As he left the courtroom, the family patriarch said, "We need justice."

Outside the Los Angeles airport area courthouse, about 50 Michael Jackson fans carried large photographs of the superstar and signs urging, "Justice for Michael." Many were the same fans who had stood vigil during the 2005 trial at which Jackson was acquitted of child molestation. Some shouted "murderer" when Murray was brought to court.

Murray recently reopened his office in Houston after months of waiting to be charged while his bills piled up.

A representative of the state attorney general's office said the California Medical Board would be filing a motion to revoke Murray's medical license to practice in California while he awaits trial.

Deputy District Attorney David Walgren tried to persuade the judge to impose a high bail of $300,000. He said in his motion that although Murray has no criminal record, he has violated court orders involving child support payments and "leads an irresponsible and financially unstable life."

Murray's lead lawyer, Ed Chernoff, objected that Murray should not be penalized for not having money. The judge said he believed $75,000 _ triple the bail in ordinary cases of this nature _ would be enough to ensure he does not flee. The bail was posted shortly after the hearing and Murray was released.

Jackson, 50, hired Murray in May to be his personal physician as he prepared for a strenuous series of comeback performances.

The single felony count of involuntary manslaughter alleges that Murray "did unlawfully and without malice, kill Michael Joseph Jackson."

To prove an involuntary manslaughter charge, prosecutors must either show that Jackson died while Murray was carrying out an unlawful act, or that his standard of care was so bad that it was grossly negligent.

The charge alleges he acted "without due caution and circumspection."

Known as "milk of amnesia," propofol is only supposed to be administered by an anesthesia professional in a medical setting because it depresses breathing and heart rate while lowering blood pressure.

At the same time the charge was filed Monday, the coroner's office released its autopsy report on Jackson. The document, previously obtained by The Associated Press, found the singer was in relatively good health and died from acute propofol intoxication.

Dr. Selma Calmes, an anesthesiologist who reviewed the report at the coroner's request, said the level of propofol in Jackson's body was akin to what would be given for major surgery. After such a dose, a patient normally would have a tube inserted in the airway to help with breathing and be ventilated by an anesthesiologist.

"The standard of care for administering propofol was not met," she wrote.

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Associated Press Writer Anthony McCartney contributed to this story.