Jurors in the involuntary manslaughter trial of Michael Jackson's doctor reached a verdict on their second day of deliberations Monday.

The jury buzzed three times at 10:56 a.m. (1:56 p.m. ET) to signal a verdict has been reached after about nine hours of deliberation. The verdict is expected to be announced, at 4 p.m. ET.

The seven men and five women must decide if Dr. Conrad Murray was criminally negligent in his use of the surgical anesthetic propofol to treat Jackson's insomnia and if it significantly contributed to the singer's 2009 death.

Jackson fans who shouted slogans, waved signs and sometimes argued with Murray supporters outside the courthouse Friday planned a more solemn verdict vigil Monday with candles, according to messages posted on fan websites.

Katherine and Joe Jackson, the singer's parents, were expected to wait with other family members at a hotel near the courthouse so they could get there quickly.

The jury deliberated for more than seven hours Friday before telling the judge it had not reached a verdict and was ready to go home for the weekend.

Jurors heard from 49 witnesses over 23 days, including Murray's girlfriends and patients, Jackson's former employees, investigators, and medical experts for each side.

They never heard from dermatologist Dr. Arnold Klein, who the defense contends got Jackson addicted to the painkiller Demerol in the last three months of his life. The defense argued Murray did not know about that addiction, which they said had fatal complications.

Los Angeles County Superior Court Judge Michael Pastor ruled Klein's testimony would not be relevant since Demerol was not found in Jackson's body by the coroner, who concluded the pop icon's death was caused by acute propofol intoxication in combination with two sedatives.

Klein, however, told In Session correspondent Jean Casarez in an interview Saturday that he used only low doses of Demerol while repairing Jackson's collapsed nose and jawline.

Medical records presented to the jury showed at least 24 visits by Jackson to Klein's office from March 12 until June 22, 2009, three days before Jackson's death. The defense previously said Jackson was given 6,500 milligrams of Demerol at Klein's clinic during those visits.

Jackson received 900 milligrams of Demerol at Klein's clinic over three days in early May, the records showed.

"I would never give a person those doses they attributed to me," Klein said.

The records are misleading because he was in Paris during most of May, Klein said. Other doctors working out of Klein's office may have given Jackson larger doses of Demerol, he said.

It was noted during testimony that no doctor's signature was on the medical records.

Murray's defense team, which is under an order from the judge not to talk to reporters about the case, did not immediately respond to Klein's comments.

Klein said he began the slow and painful process of rebuilding some of Jackson's facial skin in early April after his nose collapsed and he lost his jaw line.

Jackson, who was preparing for his comeback concert tour, wanted to look his best, Klein said. "Michael was an absolute perfectionist," he said.

While Klein insisted Jackson was not addicted to Demerol, he claimed he was "totally addicted to propofol."

Klein said he personally tried several times to prevent other doctors from administering propofol to Jackson for sleep.

"I knew this problem existed," Klein said in the interview Saturday. "I did my best to prevent it. Whenever I could, I prevented it, but I'm only one man and I have to support my own life and take care of myself."

Prosecutor David Walgren told jurors Thursday the evidence that Murray caused Jackson's death is "overwhelming" and "abundantly clear," while defense lawyer Ed Chernoff argued no crime was committed.

"If it were anybody else but Michael Jackson, would this doctor be here today?" Chernoff asked, saying it's a negligence case that should instead be heard by the state medical board.

"He was just a little fish in a big, dirty pond," Chernoff said, pointing the finger at other doctors who treated Jackson, and at Jackson himself.

Prosecutors argue that Murray's use of propofol in Jackson's home to treat his insomnia was so reckless, it was criminally negligent.

"Conrad Murray left Prince, Paris and Blanket without a father," Walgren said. "For them, this case doesn't end today, or tomorrow. For Michael's children, this case will go on forever, because they do not have a father. They do not have a father because of the actions of Conrad Murray."

Walgren argued that until Jackson's death, no one ever heard of propofol being in a home every night to put someone to sleep. He called it "a pharmaceutical experiment on Michael Jackson … an obscene experiment."

The defense contends Jackson self-administered the fatal overdose of drugs in a desperate search for sleep without Murray's knowing.

"What they're really asking you to do is to convict Dr. Murray for the actions of Michael Jackson," Chernoff said.

After Chernoff finished his arguments, Walgren attacked the defense for trying to blame "everybody but Conrad Murray, poor Conrad Murray."

Walgren painted Murray as a selfish doctor who agreed to take $150,000 a month to give Jackson nightly infusions of propofol in his home, something an ethical doctor would never do because of the dangers.

Jurors heard from two anesthesiology experts who offered competing theories, Dr. Steven Shafer for the prosecution and Dr. Paul White for the defense.

Walgren attacked White for his determination "to find a theory or way to blame it on Michael Jackson."

White testified that the levels of propofol and sedatives found in Jackson's stomach, blood and urine during the autopsy convinced him that Jackson swallowed a large dose of lorazepam and later gave himself a rapid injection of propofol, which led to his death.

"What you were presented from Dr. White was junk science," Walgren said.

Chernoff defended his expert and attacked Shafer, saying he was "not a scientist; he was an advocate. He was trying to prove a point; he was trying to prove a case."

Shafer testified that the "only scenario" in Jackson's death was one involving an intravenous drip system infusing a steady flow of propofol into Jackson over several hours before his death.

Murray, if convicted, faces up to four years in prison and the loss of his medical license.