By Alan Duke, CNN
Los Angeles (CNN) -- Michael Jackson's two oldest children, Prince and Paris, watched from a bedroom doorway as Dr. Conrad Murray tried to revive their father, according to a security guard.
"Paris screamed 'Daddy!' and she started crying," Alberto Alvarez testified at a preliminary hearing for Murray, who is charged with involuntary manslaughter in Jackson's death in June 2009.
Michael Jackson's parents, three sisters, and brother Randy listened from the second row of the Los Angeles County courtroom as Alvarez, apparently near tears, described the scene.
"Dr. Murray then said 'Get them out, get them out. Don't let them see their father like this,'" Alvarez said. "I turned to the children and I told them 'Don't worry, children, we'll take care of it. Go outside please.'"
The Los Angeles Superior Court preliminary hearing, which began Tuesday, is expected to last two or three weeks, with 20 to 30 witnesses testifying. Judge Michael Pastor will determine whether there is probable cause to send Murray to trial.
On Tuesday, Jackson's former security chief testified that Murray seemed not to know how to administer cardiopulmonary resuscitation as he waited for paramedics to arrive at the singer's house.
Faheem Muhammed said he and Alvarez saw Murray crouched next to Jackson's bed "in a panicked state asking, 'Does anyone know CPR?'"
"I looked at Alberto because we knew Dr. Murray was a heart surgeon, so we were shocked," Muhammed said.
When defense lawyer Ed Chernoff asked if perhaps Murray was only asking for help because he was tired, Muhammed said, "The way that he asked it is as if he didn't know CPR."
Jackson appeared to be dead at that time, with his "eyes open and his mouth open, just laying there," Muhammed said.
Los Angeles County Deputy District Attorney David Walgren earlier said that Murray used "ineffectual CPR with one hand while the patient was prone on a soft bed." Using two hands with the patient prone on a hard surface is the proper method, he said.
Muhammed, the third witness on the opening day of the hearing, said he never saw Murray performing CPR on Jackson before paramedics arrived and transported the singer to Ronald Reagan UCLA Medical Center.
Muhammed's testimony on Tuesday also described Prince and Paris watching from the bedroom door.
"Paris was on the floor on her hands and knees and she was just crying," he said.
The children would learn two hours later, when Murray and Jackson manager Frank Dileo talked to them in a hospital room, that their father had died.
"Frank blurted out and said, 'Your daddy had a heart attack and died,'" Jackson personal assistant Michael Williams testified.
The hearing began Tuesday with a prosecutor saying that Murray waited at least 21 minutes after he found Jackson unresponsive before calling for an ambulance.
"By all accounts, Michael Jackson was dead in the bedroom at 100 North Carolwood prior to the paramedics' arrival," Walgren said.
The coroner concluded Jackson died from "acute propofol intoxication," in combination with "the contributory effects of the benzodiazepines," he said.
Propofol is a powerful anesthetic used to "put people under for surgery," and the benzodiazepines were sedatives Murray later acknowledged giving Jackson in the morning before his death, he said.
"Michael Jackson was preparing for one of the most important tours of his life" in the months before his death, Walgren said.
Murray's defense team has hinted it would argue that Jackson was under pressure from the concert promoter, which led him to demand treatments to help him sleep.
Kenny Ortega, who was directing what would have been Jackson's comeback concerts, was the first of about 30 witnesses to be called by the prosecution.
Ortega described Jackson as "involved, active, participating" at his last rehearsal, which ended just 12 or 14 hours before the singer died.
"He was in a delightful mood and we had an absolutely fantastic day," Ortega testified.
But Ortega described a different, "scary" Michael Jackson at the Staples Center rehearsal on June 19, six nights before his death.
"I just felt that he appeared, you know, really lost," Ortega said. "It was scary. I didn't know what was wrong. I couldn't put my finger on it."
Ortega suggested to Jackson that he cut his rehearsal short and go home to rest.
He was called to a meeting at Jackson's home the next day, where he was "scolded" by Murray for having sent Jackson home the night before, Ortega said.
"Dr. Murray told me that this was not my responsibility and he asked me not to act like a doctor or psychologist," he said.
Ortega said it was an emotional meeting, but he denied yelling at Jackson. "It wasn't yelling," he said. "It was about caring."
"Michael said, 'I know you love me and I know you care about me, but you don't have to worry. I'm fine,'" Ortega said. "It was Michael's voice that calmed me."
Randy Phillips, the CEO of concert promoter AEG Live, and Dileo were at this meeting, along with Murray and Jackson, Ortega said.
A civil lawsuit filed last year by Michael Jackson's mother against AEG Live alleged that Phillips visited Jackson's home on June 18, 2009, to warn "that if Jackson missed any further rehearsals, they were going to 'pull the plug' on the show."
"AEG told Murray that he had to make sure Jackson got to rehearsals," Katherine Jackson's lawsuit charged.
The prosecutor told the judge that medical experts would testify that Murray, hired as Jackson's personal physician while he prepared for his concert tour, took "a number of actions" that "showed an extreme deviation from the standard of care."
In addition to the CPR performed by Murray that the prosecutor described as "ineffectual," this would include administering propofol in a home setting without proper monitoring. No medical equipment that could have monitored Jackson's pulse and breathing were found in the upstairs bedroom, Walgren said.
The 20-minute delay in calling 911 for paramedics was contrary to standard care, he said.
When paramedics arrived, Murray failed to tell them about the propofol or other drugs given to Jackson that morning, Walgren said. That, too, was contrary to standard care, he said. Murray also neglected to tell emergency room doctors who were trying to revive Jackson at Ronald Reagan UCLA Medical Center about the drugs, Walgren said.
Murray remains free on $75,000 bond.
InSession Producer Michael Christian contributed to this report.
