Shizuo Kambayashi / Invision/AP 1 / 3
Shizuo Kambayashi / Invision/AP 1 / 3

The head of the Los Angeles Police Department isn't ruling out murder in the investigation into the death of singer Michael Jackson.

"We are still awaiting corroboration from the coroner's office as to cause of death. That is going to be very dependent on the toxicology reports that are due to come back," Police Chief William Bratton told CNN. "And based on those, we will have an idea of what it is we are dealing [with]: Are we dealing with a homicide or are we dealing with accidental overdose?"

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Detectives are investigating the singer's history of using prescription drugs and have spoken to a number of doctors who had treated Jackson over the years.

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Doctors who did not cooperate with investigators were issued subpoenas, according to CNN. If needed, authorities will issue more, the network reports.

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Bratton said his department also was being helped by other agencies, including the Drug Enforcement Administration, on "a comprehensive set of inquiries".

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"At the time of the death, with search warrants, we were able to seize a number of items from the residence where the death occurred and those will assist in the investigation," he added.

Though Bratton did not elaborate on what police found, The Associated Press and The Los Angeles Times both said police discovered the powerful sedative Diprivan, in addition to numerous bottles of prescription drugs, in Jackson's $100,000-a-month rented mansion in L.A.'s Holmby Hills, where he suffered cardiac arrest June 25.

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Meanwhile, the New York Post is reporting that, as it awaits burial, the casket containing Jackson sits in a temporary resting place a Forest Lawn-Hollywood Hills Court of Remembrance crypt belonging to Motown founder Berry Gordy, as the Jackson family discusses where to bury the King of Pop.