The former actor passed away on April 10, aged 76, and Malcolm LaVergne - Simpson's long-time lawyer - has now confirmed his cause of death to PEOPLE.
In May 2023, Simpson announced that he'd been diagnosed with cancer, and LaVergne admits that he thought that the controversial star had beaten the disease at one point in time.
He said: "I was pretty certain it was prostate cancer; ultimately, that was the cause.
"He thought it had beaten it. I thought this was done, but you know how cancers go. They come back, and they come back with a vengeance."
Simpson's death was announced by his family on April 11, one day after he passed away.
In a statement posted on X, they said: "On April 10th, our father, Orenthal James Simpson, succumbed to his battle with cancer.
"He was surrounded by his children and grandchildren. During this time of transition, his family asks that you please respect their wishes for privacy and grace -The Simpson Family (sic)"
Simpson's private funeral took place on April 17 at Palm Mortuary in Las Vegas.
LaVergne subsequently told RadarOnline.com:
"Others were present, but I'm not disclosing who."
In 1995, Simpson was found not guilty of the murders of his second wife Nicole Brown and her friend Ron Goldman. However, two years later, a separate civil trial jury found him liable for their deaths and he was ordered to pay out $33.5 million to their families.
Shortly after his death, Simpson's lawyer insisted he would make sure their families got "nothing" from his estate, but later backtracked on his remarks.
LaVergne told The Hollywood Reporter: "I can tell you in advance, [Ron's father] Fred Goldman’s claim will be accepted. And his claim will be handled in accordance with Nevada law."
Bang Showbiz