"It's abnormal," he told The Associated Press from Chicago a day after visiting the Jackson family. "We don't know what happened. Was he injected and with what? All reasonable doubt should be addressed."
People close to Jackson have said since his death that they were concerned about the superstar's use of painkillers. Los Angeles County medical examiners completed an autopsy yesterday and said Jackson had taken prescription medication.
Medical officials also said there was no indication of trauma or foul play. An official cause of death could take weeks.
The coroner's office released the body to Jackson's family Friday night. There was no immediate word on whether the second autopsy was being performed right away. Jesse Jackson described the family as grief-stricken.
"They're hurt because they lost a son. But the wound is now being kept open by the mystery and unanswered questions of the cause of death," he said.
Two days after Jackson died at a Los Angeles hospital, his most famous sister, Janet, arrived at the mansion Jackson had been renting. She drove up in a Bentley and left without addressing reporters.
Moving vans also showed up at the Jackson home, leaving about an hour later. There was no indication what they might have taken away.
There was also no word from the Jackson family on funeral plans. Many of Jackson's relatives have gathered at the family's Encino compound, caring there for Jackson's three children.
A person close to the family told The Associated Press they feel upset and angry about a lack of information about those who were around the pop superstar in his final days. The person requested anonymity because of the delicate nature of the situation.
Jackson had been rehearsing for 50 London concerts aimed at restoring his crown as the King of Pop. He died Thursday at age 50 after what his family said appeared to be cardiac arrest.
A 911 call from Jackson's rented home reported that his personal doctor was trying to revive him without success. Police have talked to Dr. Conrad Murray and have said they intend to speak with him again but have stressed he is not a criminal suspect.
Murray has yet to speak publicly since Jackson's death. Police towed his car from Jackson's home hours after Jackson died and said later it could contain medication or other evidence. Coroner's officials also said Jackson was taking prescription medication but declined to elaborate.
A lawyer at a Houston firm, William M. Stradley, confirmed Murray had hired his firm and said one of its partners was meeting with Los Angeles police on Saturday. Stradley said Murray accompanied Michael Jackson to the hospital.
"He was there from the beginning and he's been cooperating with police from the very beginning," Stradley said. "Dr. Murray has never left L.A. since Mr. Jackson's death, and he remains there."
Murray lives in Las Vegas but apparently left his practice and moved in with Jackson about two weeks ago. No one answered the door Saturday at his Las Vegas home, which property records show Murray bought five years ago for $1.1 million.
The promoter of the series of London concerts that Jackson was to begin next month has said Jackson personally insisted Murray be on the payroll.
Also Saturday, spiritual teacher Dr. Deepak Chopra said he had been concerned since 2005 that Jackson was abusing prescription painkillers and most recently spoke to the pop star about suspected drug use six months ago.
Chopra said Jackson, a longtime friend, asked him for painkillers in 2005 when the singer was staying with him following his trial on sex abuse allegations. Chopra said he refused. He also said the nanny of Jackson's children repeatedly contacted him with concerns about Jackson's drug use over the next four years.
He said she told him a number of doctors would visit Jackson's homes in Santa Barbara County, Los Angeles, Miami and New York. Whenever the subject came up, Jackson would avoid his calls, Chopra said.
