Elvis Presley's ex-wife, Priscilla Presley, candidly opens up about the King of Rock-'n'-Roll's final years, and his painful drug addiction, during the debut of "Elvis Presley: The Searcher" at SXSW.

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Elvis Presley may have passed away more than 40 years ago, but the life that he lived continues to fascinate people across the globe.

As fans know, during his final years, Elvis was deeply addicted to prescription drugs. His ex-wife, Priscilla Presley, is now opening up about the unfortunate addiction that sadly led to the late musical icon’s tragic death in 1977.

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According to Fox News, Priscilla, who helped produce a documentary that honors the King called "Elvis Presley: The Searcher," spoke about her ex-husband's issue with substance abuse during the movie's debut at the South by Southwest Film Festival (SXSW) in Austin, Texas, on March 14.

"It was difficult for all of us. We certainly didn't see it coming," she said of Elvis' unfortunate passing at the age of 42. "But we certainly saw the journey he was taking."

She also added, “People go, ‘Well, why didn’t anyone do anything?’ Well, that’s not true. People there in the inner group did, but you did not tell Elvis Presley what to do. You did not. I mean, you’d be out of there faster than a scratched cat. They would try and no way. He knew what he was doing.”

Elvis and Priscilla met in 1959 while he was serving in the U.S. Army. During the candid discussion at SXSW, Priscilla also noted that he started taking pills when he was stationed in Germany.

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“They gave them to the soldiers over there to keep them awake,” she said. “He was on guard at that time. He had maneuvers that he had to do late at night, so the pills were given to the guys, and that’s how he started. And if you take a sleeping pill, you have to do something to get yourself awake … He was in unchartered territory, he truly was, and he did this and tried to do this alone.”

Fans can learn more about the late star in "Elvis Presley: The Searcher." The documentary, which chronicles his creative journey from early childhood through his final recording session, held in the famous Jungle Room of his Graceland estate in Memphis, Tennessee, premieres April 14 on HBO.