A search warrant made public in Houston showed that a high dosage of the anaesthetic propofol was in the star's system when he died at his rented home in LA on June 25.

Police investigating the late singer's death have reportedly been working on the theory that the singer's personal doctor, Conrad Murray, administered the medication to help Jackson sleep hours before he collapsed.

It has also been reported that the Los Angeles County coroner had ruled Jackson's death a homicide, with the Associated Press citing a law enforcement official as its source for this.

Captain John Kades, of the coroner's department, said he was not in a position to confirm or deny the report, adding "We have not released any information on the Jackson case. We do not know where this information is coming from."

The court document made public today by the LA Times reveals that Dr Murray told police he had administered several drugs to Jackson to help him sleep, including propofol. But he feared that the singer was becoming addicted to the drug and halved his dosage from 50 milligrams a night to 25 milligrams.

Dr Murray reportedly told officers that on the day of Jackson's death he tried to induce sleep without the use of propofol. But after giving the singer a cocktail of other drugs, he turned to propofol following persistent requests from Jackson himself.

Dr Murray has increasingly become the focus of police efforts to establish the cause of Jackson's death.
SOURCE : AP