LOS ANGELES (AP) - Testimony has resumed in the involuntary manslaughter case against the doctor charged in Michael Jackson's death.
Prosecutors called an executive from a company that manufactures a device that measures pulse and oxygen levels in the blood. Authorities recovered the $275 device after Jackson's death.
Nonin Medical executive Bob Johnson told jurors Friday that the model had no audible alarm and is not intended to be used for continuous monitoring of patients.
Prosecutors have said Dr. Conrad Murray lacked the proper monitoring and life-saving equipment when he was giving Jackson doses of the surgical anesthetic propofol.
Murray has pleaded not guilty.
Jurors are expected Friday to hear from paramedics who responded to the singer's rented mansion and tried to revive him.
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Paramedics who responded to Michael Jackson's mansion the day he died were expected to testify Friday in the trial of the pop star's doctor who has been charged with involuntary manslaughter.
Martin Blount and Richard Senneff had previously testified at a preliminary hearing that Dr. Conrad Murray never mentioned giving Jackson the powerful anesthetic propofol and told them the singer lost consciousness moments before an ambulance was called. Both men believed the singer had died by the time they arrived in June 2009, but Murray insisted the performer be taken to a hospital for more resuscitation efforts.
The prosecution witnesses will likely provide jurors more insight into Jackson's final moments as futile attempts were made to revive the unresponsive superstar as the trial enters its fourth day.
On Thursday, a pair of Jackson staffers described the chaotic scene at the rented mansion. Personal chef Kai Chase said she was preparing a spinach Cobb salad for Jackson when a panicked and flustered Murray came down a spiral staircase shouting for her to get security and the singer's son, Prince.
"His energy was very nervous and frantic," said Chase, who added she ran to get Jackson's son in a nearby room. "I said, `Hurry, Dr. Murray needs you. Something may be wrong with your father."
Chase said later she saw paramedics and security running upstairs to Jackson's bedroom where he lay and some of the house staff were crying, unsure of what was happening.
"The children were crying and screaming," she said. "We started hugging. We came together, held hands and we began to pray."
Bodyguard Alberto Alvarez said he went to help Jackson after the singer's assistant called him on his cellphone. Shocked at seeing Jackson lying motionless in his bed, eyes slightly open, Alvarez barely had time to react when he heard the singer's daughter scream "Daddy!" from the doorway. He led her and Prince from the room, trying to comfort them.
Alvarez then said Murray told him to put vials of medicine he scooped from Jackson's nightstand into a bag. Alvarez complied and also placed an IV bag into another bag.
Alvarez's testimony was key for prosecutors who contend Murray, who has pleaded not guilty, was intent on concealing signs that he had been giving the singer doses of propofol as a sleep aid.
Alvarez said he thought Murray might be preparing to take the items to the hospital, but the bags never made it to the hospital and the bodyguard never questioned the doctor.
If convicted, Murray, 58, could face up to four years in prison and lose his medical license.
Defense attorney Ed Chernoff asked whether there was enough time for Alvarez to shield Jackson's children, survey the room and stow away the drugs in the brief period that phone records show he was in the home before calling emergency responders.
The bodyguard insisted there was, telling the attorney, "I'm very efficient, sir."
Chernoff was not convinced, questioning whether 30 seconds was enough time for the dramatic sequence to play out. Alvarez assured him there was.
The defense attorney also challenged Alvarez's recollection, asking whether the collection of the vials happened after paramedics had come and whisked Jackson to a nearby hospital. Alvarez denied it happened after he called 911.
Chernoff questioned why Alvarez didn't tell authorities about Murray's commands to bag up the medication immediately after Jackson died, but instead waited until two months after the singer's death. The bodyguard said he didn't realize its significance until seeing a news report in late June in which he recognized one of the bags detectives were carrying out of Jackson's mansion.
The burly Alvarez became emotional as the 911 call was played for jurors. Jackson's mother, Katherine, appeared distraught and her son, Randy, huddled next to her and put his arm around her.
"Was that difficult to hear?" prosecutor David Walgren asked.
"It is," Alvarez replied.
Alvarez's testimony allowed Walgren to present jurors directly with a bottle of propofol that they've heard much about throughout the previous two days of the trial.
Jurors intently looked at the bottle, which appeared to still contain some liquid.
Walgren asked whether anything good had happened to Alvarez as a result of his experience in Jackson's bedroom.
"No sir," Alvarez responded.
Media outlets reportedly offered him up to $500,000 for interviews, but Alvarez said he always refused. "It's caused a lot of financial problems," he said, starting to choke up. "I went from a great salary to hardly anything."
AP Entertainment Writer Anthony McCartney contributed to this report