Joe Jackson, 80, who had sought a private autopsy of the pop star after a preliminary autopsy report ruled out foul play in the death, said that the family wants to know why the pop star died suddenly.

"I just couldn't believe what was happening to Michael. I do believe it was foul play. I do believe that.

Yes," Joe told ABC news in an interview adding that the private autopsy revealed nothing new.

Jackson, 50, died after a suspected cardiac arrest on June 25, He was on the verge of making a much awaited comeback just weeks before his death.

The LA County coroner's office is awaiting toxicology results in Jackson's death before listing the cause of death.

Meanwhile, the Los Angeles Police Department is investigating the role of prescription drugs in the circumstances surrounding the singer's death, the Los Angeles Times reported.

Earlier, reports had claimed that detectives recovered numerous prescription drugs from Jackson's rented home, including a powerful anesthetic that is normally used only at hospitals during operations.