Mickey Rooney Jr Cause of Death Mysterious: Willie Nelson's Band Member Dead at 77

Musician and actor Mickey Rooney Jr. has died. He was 77.

Rooney, the eldest son of Hollywood legend Mickey Rooney, reportedly died at his home in Glendale on Saturday. Several loved ones confirmed the news to different news outlets and social media sites.

His longtime companion, Chrissie Brown, informed The Hollywood Reporter about his passing but did not disclose his cause of death.

Meanwhile, former actor and founder of advocacy group A Minor Consideration Paul Petersen addressed the tragic news through a Facebook post. Like Brown, he did not share what led to his passing but told everyone that he peacefully died.

"I was born on the same day as Mickey's father and "The Mic" gave me, unsolicited mind you, the most useful advice I ever got. It is one of my greatest sorrows that he didn't do the same for his son. Mickey Rooney Junior. Rest In Peace at last. We will see to your wishes," he wrote.

A Minor Consideration launched a GoFundMe page to support Rooney Jr.'s memorial expenses. It set its goal to $25,000, and 15 donors already shared their love for the late star's bereaved family.

Mickey Rooney Jr.'s Legacy

Rooney Jr. was a multi-talented star before his death.

Walt Disney first hired him in 1955 to become part of the original Mouseketeers for "The Mickey Mouse Club." However, he, his brother Tim Rooney, and Petersen were fired before the end of the first season.

Rooney Jr. went on to show his acting and musical skills. In 1967, he was tapped to appear in "Hot Rods to Hell" and "Beyond the Bermuda Triangle" in 1975.

During the 1960s, Rooney Jr. created a band with his brother Tim and graced the stage of the TV music show, "Shindig!" He could play keyboard, bass, drums, harmonica, and guitar. He also got the chance to play in bands with Willie Nelson.

"My grandmother, Nanny Rase, had a ukulele. When I was 11 years old, she asked if I would like her to show me some chords. I could play the chords she showed me. I put those chords to use on a classical guitar, and I was hooked," he told Riverside Press-Enterprise newspaper in 2001, as quoted by Yahoo!.

Years later, he and Nelson worked together in the 1980 "Honeysuckle Rose."

Amid the success he enjoyed, Rooney Jr. faced substance-abuse issues. But he later became a born-again Christian and founded an evangelical ministry.

He was the first child of Mickey Rooney and Betty Jane Baker, a singer and 1944 Miss Alabama.