There have been several theories over the years as to the main cause of Elvis Presley’s untimely death at just 42 on August 16, 1977.

The King of Rock and Roll died of a heart attack while reading on the toilet of his ensuite bathroom at Graceland after months of weight gain and prescription drug addiction contributed to already present health problems.

Now, in an exclusive interview with Express.co.uk, Elvis’ step-brother David Stanley has blamed the star’s personal doctor, Dr George Nichopoulos – who died in 2016 – for the singer’s demise.

Speaking from the Las Vegas stage at the Westgate (formerly International Hotel) where the King performed his residencies, the Memphis Mafia bodyguard didn’t hold back.

David shared: “[Isolation] was part of his demise… he had no accountability… When I talk about Elvis, I talk about his medications costing him his life. I'm very adamant about it, very vocal about it. Fans go, ‘How could you talk that way about Elvis?’ Be there for five years, the last years of his life, watch him go from King to 255 pounds – those were his words – totally wrecked, and do the job to keep him there alive as long as he can. Whether it be too much food, whether imbalance from his water because of the medications, go through all of that, then come to me and tell me how much you love Elvis.

“Because I was there every day, and the hardest thing for me was to watch that self-destructiveness, nothing could stop him. To watch that self-destructive spirit… and I walked into his bathroom, and then he was gone. I wish the people could have known that guy, not because I wanted to be tarnished by his actions, but true love is not a fan base. True love is caring, no matter what.”

On Elvis’ personal doctor, David said: “Dr Nick gave him over 10,000 pills in the last eight months of his life. Without Dr Nick, Elvis would have died in 21st Century, Nick would be in prison and would have died in prison. The doctors killed him… who needs 10,000 pills? Who needs 33 sleeping pills to go to sleep at night? Who needs cocaine and amphetamine to wake up every day? And they say he had health problems… my friend, you take as much dope as that, you’re going to have some health problems.”

Asked if he was surprised when he found Elvis’ corpse on the floor of his Graceland bathroom, the King’s step-sibling said: “Oh no, I used to sit around with [Memphis Mafia member] Lamar Fike and say, ‘He’s never going to see Winter’… I knew with Elvis it was just a matter of time. We were blessed that he didn't die on a stage somewhere.”

He and the other Memphis Mafia men would take shifts to watch Elvis 24/7 “because it got that bad.” Two days before he died on August 16, 1977, David saw Elvis for the last time ahead of going on a tour that would never happen. During this encounter with the star (who his brother compared to a modern-day King David struggling with the temptations of the world but “always going back to the Word of God”), he predicted he was about to die.

The King’s brother remembers seeing Elvis in his room and being asked: “David, who am I?” He recalled: “[Elvis is] reading his Bible. I said, ‘You’re the King, man’ and he goes, ‘No there’s only one King’ [referring to Jesus Christ]. He stood up, he gave me a hug. He said, ‘I want you to know I love you, but the next time you see me, I’ll be on a higher plane.’ I looked around at the [spiritual] books he’d been reading and I thought, ‘He’s been reading something’. And I said, ‘I’ll see you on the 16th in two days on the Lisa Marie [private jet]. I walked out the door and I turned around and looked at him and he said, ’On the 16th, David’ and two days later I saw him dead’”

The 68-year-old, who has also struggled with his own drug addiction before getting sober, added: “He knew what he was doing, and so when I walked in that day, I was mad. ‘How could you leave me like this, like the rest of the world?’ But for me, it was big brother, and then I had a peace about it. ‘This is time for the boy to go home. God took him home.’”

My Brother Elvis: An Evening with David Stanley, which includes a tour of the backstage where The King performed, is held monthly at Westgate, Las Vegas, and tickets can be booked here.