Los Angeles (CNN) -- Michael Jackson slurred his speech after visits to Beverly Hills dermatologist Dr. Arnold Klein, trips that became "very regular" for the pop star in the weeks before his death, Jackson's personal assistant testified Wednesday.
Defense lawyers for Dr. Conrad Murray, who is on trial for involuntary manslaughter in Jackson's death, contend that Klein addicted the singer to Demerol during those visits, something Murray did not know about.
His withdrawal from that Demerol addiction was what kept Jackson awake despite Murray's efforts to put him to sleep with sedatives the morning he died, the defense contends, arguing that Klein is at least partly responsible for Jackson's death because of the Demerol.
Michael Amir Williams, who worked for Jackson the last two years of his life, was asked by defense lawyer Ed Chernoff whether he went to Klein's office with Jackson.
"At a certain point, it was very regular," Williams said.
Chernoff then asked Williams whether he'd ever heard Jackson talk slowly with slurred speech, as he did on an audio recording played in court Tuesday.
"Not that extreme, but I have heard him talk slow before," Williams said.
"And when he left Dr. Klein's office, have you observed him sometimes to talk slow?" Chernoff asked.
Sometimes, Williams replied, "he would talk slow like that. I never heard it that extreme, but I can definitely say he has come out, and he's a little slower."
Jackson security guard Faheem Muhammad, who often drove Jackson, followed Williams on the witness stand Wednesday afternoon.
"There were times he would go almost every day" to Klein's office, and Jackson often appear intoxicated when he left, Muhammad testified.
Jackson once told Muhammad that his frequent trips to the dermatologist were for treatment for a skin disease.
"My doctors tell me that I have to go, so I go," Muhammad said Jackson told him.
At the start of court proceedings Wednesday, Paul Gongaware, an executive with the company promoting Jackson's comeback concerts, said he noticed that Jackson had "a little bit of a slower speech pattern, just a slight slur in the speech" after a visit with Klein.
Medical records show that Klein gave Jackson numerous shots of Demerol in the weeks before his death, Chernoff told jurors Tuesday.
Jackson's inability to sleep the morning he died was "one of the insidious effects" of Demerol addiction withdrawal, Chernoff said. Since Murray did not know about the Demerol, he could not understand why Jackson was unable to fall asleep that morning, Chernoff said.
Los Angeles County Superior Court Judge Michael Pastor previously ruled that while the jury can see some of the records of Klein's treatment of Jackson, the doctor would not testify. Demerol was not found in Jackson's body during the autopsy, which makes Klein's testimony irrelevant, Pastor ruled.
Testimony from Williams and Muhammad included emotional details about the chaos in the Jackson home and at the hospital the day Jackson died.
Williams described Wednesday a frantic series of phone calls that started at 12:13 p.m. June 25, 2009, the day the pop icon died.
"Call me right away, please, call me right away," Murray said in a voice message to Williams, which prosecutors played in court Wednesday.
"Get here right away; Mr. Jackson had a bad reaction," Williams said Murray told him when he called him back.
Williams then ordered a security guard to rush to the upstairs bedroom where Murray was working to resuscitate Jackson.
Muhammad, one of those ordered upstairs, described seeing Jackson on a bed with his eyes open and his mouth "slightly opened" as Murray tried to revive him.
"Did he appear to be dead?" Deputy District Attorney David Walgren asked.
"Yes," Muhammad replied.
Jackson's two oldest children were standing just outside the room, watching in shock, Muhammad said.
"Paris was on the ground, balled up, crying. And Prince, he was standing there, he just had a real shocked, you know, slowly crying, type of shocked look on his face," he said.
His description of Murray's efforts to revive Jackson raised questions about Murray's knowledge of how to perform CPR.
It was several minutes before the guard called for an ambulance.
Williams and Muhammad later rode with Jackson's three children to Ronald Reagan UCLA Medical Center, following the ambulance that carried their father.
Jackson family members slowly arrived at the emergency room and joined the children, who were kept in a private room with their nanny while doctors tried to revive their father, Williams said.
"Dr. Murray and the doctors walked out, and they closed the curtain and said, 'He's dead,' " he testified.
Williams described what he called an odd request by Murray at the hospital for a ride back to Jackson's home after he was pronounced dead.
Murray told Williams he needed to go back to retrieve "some cream" from Michael's bedroom that Jackson "wouldn't want the world to know about."
The prosecution contends that Murray wanted to retrieve evidence of his medical misconduct that led to Jackson's death.
A lawyer hired by concert promoter AEG to draw up the contract with Murray testified that Murray requested a cardiopulmonary resuscitation machine and money to hire a second doctor to help him care for Jackson.
The additional doctor and the CPR equipment were never provided, since the contract was not signed before Jackson died, attorney Kathy Jorrie testified.
She told the court that it was her understanding that Murray did not want the CPR unit or the additional doctor until he arrived in London with Jackson in July 2009 for the "This Is It" concerts.
"I asked Dr Murray, why do we need a CPR machine?" Jorrie testified.
Murray told her he needed it since "given (Jackson's) age and the strenuous performance he would be putting on, that if something went wrong, he would have it," she said.
The second doctor would be necessary because "if (Murray) was tired or unavailable, he wanted to make sure there was someone else to be of assistance" to Jackson.
AEG is being sued by Jackson's mother, Katherine, based on her contention that the concert promoter hired and controlled Murray when he was caring for her son.
The prosecution contends that part of the negligence that makes Murray criminally liable for Jackson's death is the lack of monitoring and CPR equipment on hand when Jackson died.
The trial began Tuesday with prosecutors playing a stunning audio recording of an apparently drugged Jackson slurring his words weeks before his death. Prosecutors also showed jurors a photo of Jackson's corpse on a hospital gurney.
Jackson's struggle to sleep between rehearsals for his "This Is It" comeback concerts is central to the prosecution and defense theories of how the entertainer died.
Walgren blamed Murray for Jackson's death, saying he abandoned "all principles of medical care" when he used the surgical anesthetic propofol to put Jackson to sleep every night for more than two months.
The coroner ruled that Jackson's death was the result of "acute propofol intoxication" in combination with sedatives.
Defense lawyer Chernoff contended that Jackson, desperate for sleep, caused his own death by taking a handful of sedatives and drinking propofol while the doctor was out of the room.
Chernoff told the jury that scientific evidence will show that, on the morning Jackson died, he swallowed a sedative without his doctor's knowledge, "enough to put six of you to sleep, and he did this when Dr. Murray was not around."
Jackson then ingested a dose of propofol on his own, creating "a perfect storm that killed him instantly," Chernoff said.
"When Dr. Murray came into the room and found Michael Jackson, there was no CPR, no paramedic, no machine that was going to revive Michael Jackson," he said.
"He died so rapidly, so instantly that he didn't have time to close his eyes," Chernoff said.
Chernoff told jurors that Murray was trying to wean Jackson off propofol when Jackson died.
Jackson's death was "tragic, but the evidence will not show that Dr. Murray did it," Chernoff told jurors.
The prosecution contends that Murray wanted to retrieve evidence of his medical misconduct that led to Jackson's death.
Murray appeared to become emotional at one point as Chernoff presented his opening statement Tuesday morning, dabbing his eyes at times. Mostly, though, the defendant remained stoic through the proceedings.
If convicted of involuntary manslaughter, Murray could spend four years in a California prison and lose his medical license.
Prosecutors played clips from Murray's interview with investigators in which he described giving Jackson a final dose of the propofol after a long, restless night when the singer begged for help sleeping.
"The evidence in this case will show that Michael Jackson trusted his life to the medical skills of Conrad Murray, unequivocally that that misplaced trust had far too high a price to pay," Walgren said. "That misplaced trust in the hands of Conrad Murray cost Michael Jackson his life."
The most dramatic moment Tuesday came when jurors heard a May 10, 2009, recording, captured by Murray's iPhone, of Jackson "highly under the influences of unknown agents," as he talked about his planned comeback concert, according to Walgren.
"We have to be phenomenal," Jackson said in a low voice, his speech slurred. "When people leave this show, when people leave my show, I want them to say, 'I've never seen nothing like this in my life. Go. Go. I've never seen nothing like this. Go. It's amazing. He's the greatest entertainer in the world.' I'm taking that money, a million children, children's hospital, the biggest in the world, Michael Jackson's Children's Hospital."
The tape, prosecutors say, is evidence that Murray knew about Jackson's health problems weeks before his death.
Jurors also saw a video of the superstar rehearsing at the Staples Center in Los Angeles the night before he died. Jackson sang and danced to "Earth Song," the last song he would rehearse on stage.
Prosecutors also presented a photo of Jackson's lifeless body on a hospital gurney, about 12 hours later.
Producer Kenny Ortega, the first prosecution witness, said Tuesday he was jolted by Jackson's appearance when the latter arrived at a rehearsal, on June 19, less than a week before he died.
"He appeared lost and a little incoherent," Ortega said. "I did not feel he was well." Ortega said he gave the pop singer food and wrapped him in a blanket to ward off chills. Jackson watched the rehearsal and did not participate that day.
Ortega was helping Jackson prepare for the "This Is It" world tour scheduled for London's O2 Arena in autumn 2009.
In an e-mail early June 20, Ortega wrote, in part, to AEG President Randy Phillips, "My concern is, now that we've brought the Doctor in to the fold and have played the tough love, now or never card, is that the Artist may be unable to rise to the occasion due to real emotional stuff."
The producer said Jackson appeared weak and fatigued on June 19.
"He had a terrible case of the chills, was trembling, rambling and obsessing," he wrote. "Everything in me says he should be psychologically evaluated. If we have any chance at all to get him back in the light. It's going to take a strong Therapist to (get) him through this as well as immediate physical nurturing. ... Tonight I was feeding him, wrapping him in blankets to warm his chills, massaging his feet to calm him and calling his doctor."
Jackson also appeared to be scared of losing the comeback tour.
"I believe that he really wants this ... it would shatter him, break his heart if we pulled the plug," Ortega wrote. "He's terribly frightened it's all going to go away. He asked me repeatedly tonight if I was going to leave him. He was practically begging for my confidence. It broke my heart. He was like a lost boy. There still may be a chance he can rise to the occasion if (we) get him the help he needs."
AEG was the concert promoter.
Murray was unhappy that Jackson did not rehearse June 19 and told Ortega not to try to be the singer's physician, Ortega testified, adding that Jackson insisted the next day he was capable of doing the rehearsals. Jackson was a full rehearsal participant in the days before he died, the producer said.
Jackson's parents, brothers Tito, Jermaine and Randy, and sisters La Toya, Janet and Rebbie filled a row in the courtroom for a second day of the trial. Jackson's three children are not expected to attend the trial or testify, according to a source close to their grandmother, Katherine Jackson.