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 US, 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 mini-trial, 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. 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 which 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. Deputy District Attorney David Walgren tried to convince 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.