Sidney Poitier's Cause of Death Was Heart Failure, Prostate Cancer and Dementia Contributed

A source previously told ET that Poitier died at his home in Beverly Hills, California.

Sir Sidney Poitier's cause of death has been revealed.

ET has learned that Poitier's primary cause of death was heart failure. The legendary actor, who died Jan. 6 at the age of 94, suffered from a combination of both prostate cancer and dementia for many years, but neither led to his death.

Clint Watson, press secretary for the Prime Minister of the Bahamas confirmed the Oscar-winning actor, writer, director and activist's death to ET the following day.

A source close to the family told ET at the time that Poitier had been bedridden for some time and passed away at his home in Beverly Hills, California. The actor's rep also told ET that his family was by his side at the time of his death.

The film and TV icon made history in 1964 as the first Black actor, and the first Bahamian, to win an Oscar and Golden Globe in a leading role, which he earned for Lilies of the Field. He became one of Hollywood’s leading men starring in a heap of classic films including,To Sir With LovePorgy and BessA Raisin in the SunIn the Heat of the Night and Guess Who’s Coming to Dinner.

Celebrities, politicians and fans have all paid tribute to the Hollywood icon, but one of the most touching tributes came from his daughter, Sydney.

The actress posted an emotional tribute to her father and his long-standing legacy on her Instagram page, opening up about their relationship and her grieving. 

"There are no words for this. No real way to prepare for this. No prose beautiful enough, no speech eloquent enough to capture the essence of my dad," Sydney wrote, adding that his accomplishments "quite literally changed the landscape for everyone who came after him" and praising him for having "blazed a trail through rough and hostile terrain so those coming behind him could have a bit more ease on the journey."

Although her father cemented his place in history with his countless on-screen accolades, Sydney wrote that she wanted fans to know the "depth of his goodness."

"...It permeated every cell of his being. The sort of goodness that prevented him from killing even the tiniest of bugs. Not a one. He knew on a cellular level that if he hurt anyone or anything, he hurt everyone and everything," she continued, explaining that her dad "treated anyone who crossed his path as his equal and offered them his full presence." 

Sydney wrote that her grief isn't only because she lost her dad, but also because "the world lost so much goodness." 

"He was like a lighthouse. Warm and bright. No matter the storms whipping around him, he stood unwavering shining his light," she shared. 

Sydney concluded her tribute by writing that although losing her dad has caused "unbearable pain" and she would miss the little things, it helps to know that his "goodness" will live on.

"I will miss you more than words can express Dad. I will feel you in the warmth of the sun on my back, I will hear you in the wind in the trees and I will look for you among the stars where you will surely be," she wrote. "I love you."

Sydney's message for her father came a few days after her family released a statement on the actor's death. In a statement to ET, the Poitier family said the iconic actor and humanitarian spent his last day surrounded by his family and friends. "There are no words to convey the deep sense of loss and sadness we are feeling right now," the statement began.

The family, for decades, took immense pride in Poitier's acting achievements, but their pride extended beyond those accomplishments. 

"To us Sidney Poitier was not only a brilliant actor, activist, and a man of incredible grace and mortal fortitude," the statement continued, "he was also a devoted and loving husband, a supportive and adoring father, and a man who always put family first. He is our guiding light who lit up our lives with infinite love and wonder."

"His legacy will live on in the world, continuing to inspire not only with his incredible body of work, but even more so with his humanity," the statement concluded. "We would like to extend our deepest appreciation to every single one of you for the outpouring of love from around the world. So many have been touched by our dad’s extraordinary life, his unwavering sense of decency and respect for his fellow man. His faith in humanity never faltered, so know that for all the love you’ve shown him, he loved you back."