Los Angeles (CNN) -- Dr. Conrad Murray's involuntary manslaughter trial has been put on hold at least until Wednesday to give the defense time to study new lab test results the prosecution contends show Michael Jackson did not ingest a fatal overdose of sedatives.
Testimony was suspended last Thursday afternoon to allow the prosecution's anesthesiology expert to attend a medical convention, and again Monday because that witness's father died.
The trial, in its fourth week, is still expected to conclude with the start of jury deliberations next week.
The Los Angeles County coroner tested Jackson's stomach contents for the level of the sedative lorazepam last Wednesday at the request of the prosecution, Deputy District Attorney David Walgren revealed at a hearing Monday.
The testing was ordered after Murray's defense contended that Jackson swallowed eight tablets of lorazepam, a sedative, in a desperate search for sleep the day he died.
The results show "a much smaller amount of lorazepam in the stomach that is totally inconsistent with oral consumption of lorazepam tablets," Walgren said.
The coroner ruled that Jackson's June 25, 2009, death was from "acute propofol intoxication" in combination with several sedatives, including lorazepam.
The defense complained that the coroner should have done the test two years ago, not during the trial.
"It's about the time," defense lawyer Ed Chernoff said. "It's about the fairness issue."
Dr. Steven Shafer, an anesthesiology expert, is crucial to the state's effort to prove Jackson's death was caused by Murray's gross negligence in using the surgical anesthetic propofol to help the pop icon sleep.
Shafer began testifying Thursday morning before the judge recessed for the weekend so he could travel to a medical convention. He never made it there because of the death in his family, Walgren said Friday.
Shafer, who is expected to give a detailed scientific explanation of how propofol is metabolized in the human body, will be on the witness stand for at least a day, according to Walgren.
Shafer's testimony is expected to echo the opinions of a sleep expert and a cardiologist who testified that Murray's treatment of Jackson was so grossly negligent that it was criminal.
The defense presentation would follow, lasting until Friday or the following Monday, according to defense lawyer Nareg Gourjian.
Along with two or three medical experts and a police officer not called by the prosecution, the defense has lined up several patients of Murray to testify about how he's helped them, Gourjian said.
There is no indication Murray will take the stand to testify in his defense, which would subject him to intense cross-examination by Walgren. The jury already heard the recording of his interview with detectives two days after Jackson's death.
Murray's lawyers contend that Jackson used a syringe to inject the fatal overdose through a catheter on his left leg while Murray was away from his bedside. They dropped the theory pushed earlier that Jackson may have orally ingested the propofol that the coroner says killed him.
The self-administered propofol, along with the eight lorazepam tablets, killed Jackson, not the drugs Murray gave him earlier in the morning, the defense contends.
Murray should be found guilty even if jurors accept the theory that Jackson self-administered the fatal dose because the doctor was reckless in leaving propofol and lorazepam near his patient when he was not around, Dr. Alon Steinberg, a cardiologist testifying for the prosecution, said last week.
"It's like leaving a baby that's sleeping on your kitchen countertop," Steinberg said. "There's a very small chance the baby could fall over, or wake up and grab a knife or something."
On Thursday, UCLA sleep expert Dr. Nader Kamangar 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.
But Kamangar, 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.
If convicted of involuntary manslaughter, the maximum sentence Murray could face is four years in prison and the loss of his medical license.