Evan Chandler was found in bed with a single gunshot to his head, cops in New Jersey said.
A concierge at the dentist's luxury waterfront apartment block stumbled on the horror in Jersey City. The gun was still in the dad's hand.
Mr Chandler's suicide - on November 5 but which only emerged last night - was being probed by baffled cops.
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The 65-year-old - whose son was 13 when he claimed in the early 1990s that Jacko molested him - left no note.
Jordy, now 29, was given a payoff worth millions by the King of Pop to prevent his allegations emerging in court.
His dad's body was found after he failed to keep an appointment with a doctor - who called the concierge to check on him.
Police confirmed: "We have ruled it as suicide because he was found with a gun held to his body.
"He had a single bullet wound to the side of his head.
"There was no note but officers did find medication in keeping with a serious medical condition."
Sources said the dad was barely recognisable from how he looked during the 13-month probe launched by Santa Barbara's district attorney into the abuse claims.
The family also sued Jacko.
Bizarrely, the dad had undergone a string of cosmetic surgery operations - mirroring those of the superstar, who died in June aged 50.
Jordy, who has always been tight-lipped about his time with Jacko, had fallen out with his parents.
Three years ago he got a restraining order against his father - claiming the dentist attacked him with a dumbbell weight.
But he was recently said to have been patching things up with his mum June, who got divorced from Evan in 1992.
Former Santa Barbara County Sheriff Jim Thomas said: "Everybody in this whole saga was touched tragically."