Los Angeles: Michael Jackson's doctor Conrad Murray was found guilty of involuntary manslaughter over the King of Pop's death in June 2009, the court clerk said.

Cheers erupted outside and someone cried out in the court room, but a grim-faced Murray himself gave no reaction when the long-awaited verdict was announced yesterday after a six-week trial in Los Angeles.

Jackson's family -- led by mother Katherine and father Joe -- were in court to hear the verdict, having braved their way through a huge media and fan scrum outside the court.

Murray faces up to four years in jail and could be banned from practicing medicine after his conviction in connection with Jackson's death from an overdose of propofol on June 25, 2009.

Since opening on September 27, the trial at Los Angeles Superior Court has heard from 49 witnesses -- 33 for the prosecution, and 16 for the defense.

In his closing arguments last week, Deputy District Attorney David Walgren said Murray caused the star's death through negligence and greed, depriving Jackson's children of their father and the world of a "genius."

Walgren, summing up an "overwhelming case" against Murray, claimed the medic concocted lies to cover his tracks -- specifically about the timeline on the day Jackson died and not telling paramedics what drugs he had given.

He alleged that Murray above all wanted to protect his USD 150,000 a month salary for looking after Jackson, describing how the doctor agreed to treat the star's insomnia with the anesthetic propofol against all medical advice.

"Conrad Murray in multiple instances deceived, lied, obscured, but more importantly, Conrad Murray acted with criminal negligence," the prosecutor told the jury.

The defense, meanwhile, argued that Jackson was a desperate drug addict who caused his own death by taking more medicines while Murray was out of the room at the star's rented mansion in Los Angeles.

Defense attorney Ed Chernoff claimed that Murray was "a little fish in a big dirty pond," alleging that key witnesses conspired to agree on a story after Jackson died.

Shortly before the verdict announcement, Jackson's sister La Toya tweeted that her brother was watching over the proceedings.

"Michael's spirit will be with us in the court room and he will make sure the right verdict is made," she tweeted.

Jackson's former dermatologist broke his silence to deny the singer was a drug addict, or that he had given him massive doses of painkillers in the months before his death.

"Michael was not a drug addict. Michael Jackson did not have a problem with pain killers," said Dr Arnold Klein, whose office Jackson visited several times a week in the months before his death.