Michael Jackson's family raised questions on Saturday about the death of the "King of Pop" as a probe into his death continued.

The Rev. Jesse Jackson, a friend of the family, said they have questions about the death, but not a lot of answers.

"It's abnormal," he was quoted by U.S. media 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."

He also said the pop star's family is seeking a second autopsy of the pop icon due to the unanswered questions.

Meanwhile, police detectives met with Jackson's in-house doctor, Dr. Conrad Murray, who was at the home when Jackson stopped breathing.

Murray's attorney, Ed Chernoff, said the doctor had nothing to do with the pop star's death and will fully cooperate with investigators. "He is not a suspect but a witness," he said.

Los Angeles Police Department officer Rosario Herrera confirmed that investigators questioned Murray, and said he was cooperating.

Jackson, 50, died at the Medical Center of the University of California in Los Angeles after being caught by a cardiac arrest.

He died days away from the start of a sold-out series of 50 concerts in London.

A county coroner's autopsy was done Friday, but officials released little information, noting that drug tests on tissue samples may take as long as six weeks.

As rumors swirled that Jackson may have stopped breathing after being given a shot of the painkiller Demerol, the family hired a private firm to conduct a second autopsy, which was completed on Saturday, said sources close to Jackson's family.

Jackson acknowledged being addicted to prescription drugs in the 1990s.

But Randy Phillips, chief executive of insurance company AEG Live, told the Los Angeles Times that Jackson passed a four-hour physical examination required to insure his London performances, and was given a clean bill of health.

Asked if the physical examination would have revealed drug use, he told the newspaper "absolutely."

Phillips also told Houston television station KHOU that Jackson had demanded that Dr. Murray be added to Jackson's payroll.

"As a company, we would have preferred not having a physician on-staff because it would have been cheaper without the hotels and travel, but Michael was insistent that he be hired," he said. "(Jackson) just said, `Look, this whole business revolves around me. I'm a machine and we have to keep the machine well-oiled,' and you don't argue with the King of Pop."

Funeral arrangements are pending, but according to ABC7, the Los Angeles police and fire departments expect a massive public memorial service.

The family has said there could also be a series of global celebrations to commemorate his life.

(Xinhua News Agency June 28, 2009)