Prince's death was due to an accidental overdose on Fentanyl, a powerful opiod, according to his official autopsy report released on Thursday.

The Midwest Medical Examiner's Office deemed the manner of the music legend's death as "accidental," listing the cause as "Fentanyl toxicity" that was "self-administered." Prince's weight is listed at 112 pounds, and his height as 5'2".

Meanwhile, Prince's toxicology results have not been released, and under Minnesota law, are not required to be. It is unknown whether Fentanyl was the only drug in the singer's system at the time of his death.

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Fentanyl -- a powerful painkiller that's approximately 50 to 100 times more potent than morphine, and 30 to 50 times more potent than heroin -- is often used as part of anesthesia to help prevent pain after surgery or other medical procedures. Side effects include drowsiness, lightheadedness, feelings of elation (euphoria), weakness, and fatigue, as well as difficulty breathing and urinating.

In late April, a law enforcement source told CBS News that prescription drugs were found in Prince's possession and at his Paisley Park estate in Chanhassen, Minnesota, at the time of his death.

A source also previously told ET that the "Purple Rain" singer had a problem with the painkiller Percocet, which began shortly after he underwent hip replacement surgery in 2010.

Prince's onetime fiancee, Sheila E., talked to ET in April, when she acknowledged the musician had problems with his hip.

"I mean, you think about all the years he was jumping off those risers," the singer recalled. "They were not low -- they were very, very high -- and to jump off that ... First of all, the Purple Rain tour and the way that they were stacked, he had those heels on. We did a year of touring [and] for him to jump off of that -- just an entire year would have messed up his knees."

"He was in pain all the time, but he was a performer," she added.

ET reached out to the Midwest Medical Examiner's Office on Thursday, which said there is "nothing to share at this time."

WATCH: Sheila E. Opens Up About Prince's 'Somber' Memorial, Plans to Turn Paisley Park Into a Museum

Prince died on April 21, at 57 years old. Carver County Sheriff Jim Olson told ET that the legendary musician was found unresponsive in an elevator when officials responded to a call at Paisley Park Studios at 9:43 a.m.

The "Raspberry Beret" singer's family and close friends gathered at his Paisley Park estate to pay their final respects in a private memorial on April 23. The musician's body was cremated, after being released to his family following the autopsy.

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