Los Angeles police chief Bill Bratton said his department was looking into Jackson's history of prescription drug use, as well as the doctors that he had seen over the years.
"Are we dealing with homicide? Are we dealing with an accidental overdose? What are we dealing with? So as we are standing here speaking, I can tell you, I don't have that information," Bratton told CNN.
Meanwhile the late pop superstar's 79-year-old father, Joe Jackson, told ABC News that was suspicious of the circumstances surrounding his son's death.
"I do believe it was foul play," he said. "I do believe that. Yes."
The Jackson family patriarch said he "just couldn't believe what was happening" when his son was rushed into hospital late last month with an apparent cardiac arrest.
The second autopsy demanded by the family following the death of their most famous member was still yet to reveal any more answers, Joe Jackson said.
Investigators have apparently zeroed in on a powerful sedative -- Diprivan -- discovered at Jackson's rented mansion after his death.
The drug is commonly used to induce unconsciousness in hospital patients ahead of major surgery and experts say it should only be administered by a trained anesthesiologist.
Jackson's long-time dermatologist Arnold Klein earlier told CNN that he had been aware the singer had used the drug in the past.
"I knew at one point he was using Diprivan when he was on tour in Germany," he said. "He was using it with an anesthesiologist to go to sleep at night and I told him he was absolutely insane."
Klein, who said he treated Jackson three days before his mysterious death, denied providing Jackson with the drugs.
Reports have also emerged of police records that include allegations Jackson used Xanax, an anti-anxiety medication, and at one time took as many 30 pills each night.
In the ABC interview Joe Jackson also made it clear what he thought was best for Michael's children Prince Michael, 12, Paris, 11, and Prince Michael II -- also known as Blanket -- seven.
"Their grandmother -- Katherine -- and I," should raise them, he told ABC. "Yes, there's no one else to do what we can do for them.
Joe Jackson, who was left out of his famous son's will, remains married to Katherine Jackson, though many believe they have separated. Michael Jackson appointed Katherine Jackson as his children's legal guardian in his will, though a final decision will be up to the courts.
Meanwhile, questions remained surrounding Jackson's final resting place.
The star's gold-plated coffin was placed in front of the stage at a Staples Center send off in Los Angeles on Tuesday, but there has so far been no confirmation about if and where the star was already buried.
Nielsen, a TV ratings group, said 31.1 million Americans tuned in for the event in which Jackson's daughter Paris, grabbed international attention with a heartbreaking eulogy to her father.
Since the event, rumors have swirled that the pop icon was interred at the Forest Lawn Cemetery in Hollywood Hills, with celebrity news website TMZ.com claiming those reports were not true.
The uncertainty over Jackson's final resting place spurred rumors that his remains may yet end up at his beloved Neverland Ranch northwest of Los Angeles.
Jackson sold more than 750 million albums during a four-decade career that was tainted by child abuse allegations, his startling physical transformation and eccentric behavior.
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"Are we dealing with homicide? Are we dealing with an accidental overdose? What are we dealing with? So as we are standing here speaking, I can tell you, I don't have that information," Bratton told CNN.
Meanwhile the late pop superstar's 79-year-old father, Joe Jackson, told ABC News that was suspicious of the circumstances surrounding his son's death.
"I do believe it was foul play," he said. "I do believe that. Yes."
The Jackson family patriarch said he "just couldn't believe what was happening" when his son was rushed into hospital late last month with an apparent cardiac arrest.
The second autopsy demanded by the family following the death of their most famous member was still yet to reveal any more answers, Joe Jackson said.
Investigators have apparently zeroed in on a powerful sedative -- Diprivan -- discovered at Jackson's rented mansion after his death.
The drug is commonly used to induce unconsciousness in hospital patients ahead of major surgery and experts say it should only be administered by a trained anesthesiologist.
Jackson's long-time dermatologist Arnold Klein earlier told CNN that he had been aware the singer had used the drug in the past.
"I knew at one point he was using Diprivan when he was on tour in Germany," he said. "He was using it with an anesthesiologist to go to sleep at night and I told him he was absolutely insane."
Klein, who said he treated Jackson three days before his mysterious death, denied providing Jackson with the drugs.
Reports have also emerged of police records that include allegations Jackson used Xanax, an anti-anxiety medication, and at one time took as many 30 pills each night.
In the ABC interview Joe Jackson also made it clear what he thought was best for Michael's children Prince Michael, 12, Paris, 11, and Prince Michael II -- also known as Blanket -- seven.
"Their grandmother -- Katherine -- and I," should raise them, he told ABC. "Yes, there's no one else to do what we can do for them.
Joe Jackson, who was left out of his famous son's will, remains married to Katherine Jackson, though many believe they have separated. Michael Jackson appointed Katherine Jackson as his children's legal guardian in his will, though a final decision will be up to the courts.
Meanwhile, questions remained surrounding Jackson's final resting place.
The star's gold-plated coffin was placed in front of the stage at a Staples Center send off in Los Angeles on Tuesday, but there has so far been no confirmation about if and where the star was already buried.
Nielsen, a TV ratings group, said 31.1 million Americans tuned in for the event in which Jackson's daughter Paris, grabbed international attention with a heartbreaking eulogy to her father.
Since the event, rumors have swirled that the pop icon was interred at the Forest Lawn Cemetery in Hollywood Hills, with celebrity news website TMZ.com claiming those reports were not true.
The uncertainty over Jackson's final resting place spurred rumors that his remains may yet end up at his beloved Neverland Ranch northwest of Los Angeles.
Jackson sold more than 750 million albums during a four-decade career that was tainted by child abuse allegations, his startling physical transformation and eccentric behavior.
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