In his new memoir titled Me, Elton John opens up on how his perception towards Michael Jackson changed following his early interactions with the King of Pop, confessing that he thought the singer was “genuinely mentally ill” in his later years.

Sir Elton said that when Jackson had been a child star, he had been very sweet, but then related how he felt that things had reached a turning point as he grew older.

The memoir has included a number of other headline-worthy anecdotes, including throwing a dinner party where he says Sylvester Stallone and Richard Gere almost came to blows over Princess Diana, sharing a joke with the Queen, his row with Tina Turner, and his difficult relationship with his mother, saying he’s glad she never met his children.

“I’d known Michael since he was 13 or 14… He was just the most adorable kid you could imagine. But at some point in the intervening years, he started sequestering himself away from the world, and away from reality the way Elvis Presley did,” he writes in the book.

The singer continued:

“God knows what was going on in his head, and God knows what prescription drugs he was being pumped full of, but every time I saw him in his later years I came away thinking the poor guy had totally lost his marbles. I don’t mean that in the light-hearted way. He was genuinely mentally ill, a disturbing person to be around.”

Jackson was known for his unusual close friendships with a number of children when he was an adult, most famously including the then-child star Macaulay Culkin.

Recalling a time he invited MJ to one of his parties, Elton John claims that the star wandered off and was found playing with his housekeeper’s son, prompting him to deduce:

“For whatever reason, he couldn’t seem to cope with adult company at all.”

Michael Jackson died in 2009 due to overdose of sedatives administered by his personal physician, Conard Murray. Earlier this year, the star was posthumously accused of child sexual abuse by two men who were friends with him as youngsters in the documentary “Finding Neverland”.