Los Angeles (CNN) -- The trial of Michael Jackson's doctor may not resume until Tuesday because the father of the prosecution's last witness died, it was revealed at a hearing Friday.

Testimony in Dr. Conrad Murray's involuntary manslaughter trial was recessed Thursday afternoon so anesthesiology expert Dr. Steven Shafer could attend a medical conference in Chicago, but Deputy District Attorney David Walgren said Friday that Shafer never made it there because of the death in his family.

Prosecutors allege Murray was criminally responsible for Jackson's death because of his gross negligence in his use of the surgical anesthetic propofol and other drugs in Jackson's home to help him sleep.

The Los Angeles County coroner ruled that Jackson's June 25, 2009, death was from "acute propofol intoxication" in combination with several sedatives, including lorazepam.

Los Angeles County Superior Court Judge Michael Pastor, who is known for keeping tight control on his courtroom, scolded and fined prosecutor Walgren and his co-counsel, Deputy District Attorney Deborah Brazil, for being a few minutes late to Friday morning's hearing.

"People, you were late this morning by six minutes," Pastor said. "What is the reason for this, please?"

"We were just running late, your honor," Walgren said. "We apologize."

"Well, this has happened before," Pastor said, before ordering Walgren and Brazil to pay a $60 fine, $10 for each minute they were tardy to court.

Walgren blamed slow courthouse elevators when he and Brazil were 15 minutes late for a hearing last month.

Shafer, who is expected to give a detailed scientific explanation of how the surgical anesthetic propofol is metabolized in the human body, will be on the witness stand for at least a day once he returns from his father's funeral, according to Walgren.

The defense presentation would follow, lasting until next Friday or the following Monday, according to defense lawyer Nareg Gourjian.

Along with two or three medical experts, the defense has lined up about a dozen patients of Murray to testify about how he's helped them.

On Thursday, a sleep expert testifying for the prosecution said Jackson "clearly" suffered from insomnia that could have been caused by Demerol, a narcotic he was getting frequently from a doctor other than Murray.

Murray's defense team contends Dr. Arnold Klein injected Jackson with 6,500 milligrams of Demerol during visits to his Beverly Hills, California, dermatology clinic in the last three months of his life, and that Murray did not know about it.

Jackson desperately sought sleep the day he died, worried that without rest he could not rehearse that night, which could force the cancellation of his "This Is It" comeback concerts, according to Murray's interview with police.

Dr. Nader Kamangar, a UCLA sleep expert testifying for the prosecution, testified that the combination of drugs Murray gave Jackson "was the perfect storm" that killed him.

"Mr. Jackson was receiving very inappropriate therapy, in the home setting, receiving very potent sedatives, including propofol, lorazepam and midazolam, without monitoring by Murray, and ultimately this cocktail was a recipe for disaster," Kamangar said.

In Session's Michael Christian contributed to this report.