In fact, the 79-year-old Jackson family patriarch was dumbfounded when he learned his 50-year-old son was being rushed to the hospital after collapsing at home on June 25, he told ABC News in an exclusive interview at the Jackson family compound in Encino, Calif.
"I just couldn't believe what was happening to Michael," he said.
"I do believe it was foul play," Jackson added. "I do believe that. Yes."
For more on Chris Connelly's exclusive interview with Joe Jackson, tune into a special edition of "Primetime: Family Secrets -- The Jackson Family: Life After Michael", Tuesday, July 14, 10 p.m. ET
The Jackson patriarch's claim comes as Los Angeles Police Chief William Bratton suggested that the singer's death could be treated as a homicide if autopsy reports indicate that Jackson had been given illicit amounts of powerful prescription drugs.
"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," Los Angeles 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?"
Speaking amid floral tributes to the late King of Pop, Joe Jackson said he wanted to know why Michael died so suddenly. He added that a second autopsy on his late son commissioned by the Jackson family has yet to reveal any answers.
Meanwhile, as world attention turned to the fate of Michael Jackson's three children, Joe Jackson left no doubt about what he thought would be best for Prince Michael I, 12, Paris-Michael Katherine, 11, and Prince Michael II, 7, also known as Blanket.
"Their grandmother -- Katherine -- and I" should raise them, he said. "Yes, there's no one else to do what we can do for them. We should keep them all together and then make them happy, feed 'em like they're supposed to be fed, and let them get rest, plenty of sleep and grow up to be strong Jacksons."
Joe Jackson, famous for catapulting his sons into superstardom via the Jackson 5, said he already sees signs Michael Jackson's children may someday follow in their father's fast-moving footsteps.
"I don't know -- I keep watching Paris," Joe Jackson said. "She … wants to do something."
"And as far as I can see, well, they say Blanket, he can really dance," he added.
The children have been under the care of Katherine Jackson at the Hayvenhurst compound in Encino since Jackson's June 25 death from apparent cardiac arrest.
But for now the family focus is on grieving for its most famous member and pushing to find out why Michael Jackson died so young, just two months shy of his 51st birthday.
Katherine Jackson, who is gearing up for a custody battle for the three Jackson children, still has a hard time even talking about her seventh child.
"She's taking it real hard," Joe Jackson said. "When you start talking about Michael she starts crying."
How Michael Jackson's Mom Can Secure Custody
Joe Jackson, who remains married to Katherine Jackson though they are believed to be separated, was left out of their son's will, which designated Katherine Jackson as legal guardian of first choice.
Whether Katherine Jackson will get to raise the kids may begin to be determined at a hearing Monday.
However, one family law expert said Michael Jackson's will is not the last word on who eventually will get custody.
"Legally, its not a binding pronouncement by Michael Jackson," said Michael J. Kretzmer, a family law attorney. "You cannot [act] like you could with a piece of property or a car, or a boat, or a piece of jewelry. You can't give your kids away. You can't bind the court. In part, that's because kids are wholly different in nature. They're not property. You have always got to look out for the best interest of the children when you're in the court."
To that end, one of the keys may be Katherine Jackson's physical vitality.
"The lawyer for Katherine is going to go into court and is going to do her very best to tell the court why Katherine is the very best, the person best suited to care for these kids," Kretzmer said.
Katherine Jackson's lawyer, he said, likely will cover "what her relationship has been, what her knowledge of kids is, what the skills to being [a] parent are, that she has the energy, capability, and stamina to keep up with three kids who are 12, 11, and 5."
Today, the mayor of Gary, Ind., said Joe Jackson will be among those at another memorial scheduled for Friday in Michael Jackson's hometown.
Joe Jackson admitted to ABC News that he has been "very demanding" with his sons and their show business dreams. But he added no one could doubt the key role he played in molding his children into the Jackson 5, and shaping the talent of Michael Jackson, the young star who would become an international sensation.
ABC News' Michael S. James contributed to this report.