Daniel Johnston, who passed out cassette tapes of his songs to fellow Austin musicians in the 1980s and eventually became renowned worldwide as a songwriter, died early Wednesday in Houston, his manager Tom Gimbel confirmed Wednesday afternoon.

Johnston had been in the hospital with kidney issues but was released Tuesday night to the assisted living facility where he had been living recently. He was found unconscious there Wednesday morning, Gimbel said.

A statement released by the family Wednesday said Johnston died of natural causes. Gimbel noted that Johnston's health "had been touch and go for awhile" with complications from diabetes and other issues.

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Dick Johnston, Daniel's older brother, said in the statement: “I always wanted Danny to feel like his own person, and in control of his own life. Since beginning to work and travel with him in about 2003, we gratefully were able to travel the entire globe for over a decade to get out before the fans. He was always, everywhere, warmly received and he at least knew he was well loved. Health issues have plagued us for years; I’m glad for the time we had.”

For years in the 1980s and 1990s, thanks to a timely clip on MTV, Johnston symbolized underground rock in Austin. His charming songs, no-fi recording style and devotion to distributing his unique music on cassette made him an indelible figure on the American margins.

Johnston also made his mark on Austin culture with the iconic "Hi, How Are You" mural at 21st and Guadalupe streets. A well-known landmark near the University of Texas and a popular spot for photos, he created it in 1993 on the exterior wall of what was then the Sound Exchange record store. The frog-like character in the mural, who also appeared on Johnston's 1983 album of the same name, is known as “Jeremiah the Innocent.”

Born Jan. 22, 1961, in Sacramento, Calif., and raised in West Virginia, Johnston moved to Austin in the early 1980s. He was working at McDonald's in Dobie Mall near the UT campus when he began circulating his songs within the local music community. The rudimentary recordings featured Johnston accompanying himself on instruments that included a toy organ and a simple drum machine.

Austin musician and DJ Jason Asnes was among those who got one of Johnston's early cassettes. "When I was 18 and playing in a local band in Austin, we’d often do shows at The Beach Cabaret," Asnes wrote in a social media post Wednesday. "Sometimes, this guy in a McDonald’s uniform would come and hand out cassettes that he made to people. At first, most thought he was a joke or a weirdo, but he kept showing up.

"Once I listened to one of his tapes, I was blown away at how good the songs were. We let him open some shows for us, as did other bands of the time. As more and more tapes got out and word started to spread, he became popular around town and later, around the world. He was always friendly and liked talking about music with strangers. We’ll miss you Daniel."

PHOTOS: Fans create memorial Wednesday at Daniel Johnston 'Hi, How Are You' mural

Help came early on from Jeff Tartakov, who began managing Johnston in the mid-1980s and played a key role in circulating Johnston's recordings far and wide. First it was Austin bands who performed his songs onstage or recorded them in the studio, including Glass Eye, the Reivers, True Believers and the Texas Instruments.

In 1985, MTV included Johnston in an Austin-focused episode of its "Cutting Edge" program. Soon, national acts became fans, including Jad Fair of Half Japanese, who recorded a 1989 album with Johnston, and members of Sonic Youth, who also collaborated with him.

After performing at the Austin Music Awards in 1990, Johnston was flying to West Virginia in a private plane with his father when he had a psychotic episode, resulting in a crash landing. They both survived, but Johnston was temporarily committed to a mental hospital. Austin Chronicle editor Louis Black wrote a story in Spin magazine that further detailed both Johnston's art and his mental health issues.

When Nirvana's Kurt Cobain wore one of Johnston's "Hi, How Are You" shirts to the MTV Video Music Awards in 1992, Johnston's fame grew exponentially. That same year, France's Lyon Opera Ballet performed a piece by renowned choreographer Bill T. Jones that was set to Johnston's music. Johnston painted the "Hi, How Are You" mural the next year.

In 1994, Atlantic Records released "Fun," the lone major-label album of Johnston's career. In an American-Statesman article that ran upon the album's release, Johnston spoke with writer Don McLeese about his lifelong ambitions as a songwriter.

“I wanted to be famous. That was No. 1 in my mind,” Johnston said. “I wanted to be the Kenny Rogers on my block. In everything that I did, the way that I acted and what I said to people, I was thinking, 'This is my plot to become famous. My fame will grow.' It was wild. I flipped out about it.”

In 1995, Austin musician Kathy McCarty recorded "Dead Dog's Eyeball," a full album of Johnston's songs. McCarty's recording of Johnston's song "Living Life" was played over the closing credits of Austin director Richard Linklater's acclaimed film "Before Sunrise."

"When I met Daniel and I first heard (his cassette) 'Hi, How Are You?’," McCarty said Wednesday, "I really felt like he was the first genuine genius I had ever personally met in my life." She remembers offering him an opening slot for Glass Eye, then nervously consulting the rest of the band, hoping they would approve. Before a rehearsal, she played them Johnston's tape.

"Everyone else in Glass Eye totally clicked with it and got it right away," she said, noting that they ended up skipping the planned rehearsal. "All we did was just listen to his tape over and over again."

In 2006, director Jeff Feuerzeig's documentary "The Devil and Daniel Johnston" became a hit at film festivals and received a theatrical release. "To my ears as a young music geek," Feuerzeig said in a statement Wednesday, "Daniel was absolutely in the pantheon of great songwriters, with Lou Reed and Bob Dylan.

"He was a songwriter's songwriter and an artist's artist. His visual art was as powerful as his songs. I was lucky to commune with him. Making that movie took about four or five years of my life and it was the best chapter of my entire life."

In 2009, Oscar-winning songwriter Glen Hansard's band Swell Season brought Johnston onstage with a children's choir to sing one of his songs on "Austin City Limits."

» Watch: Daniel Johnston performing at the Belmont during SXSW 2012

Johnston's best-known and most enduring song is "True Love Will Find You in the End," which initially appeared on his 1984 cassette "Retired Boxer." Among those who covered it over the years were Grammy winners Beck and Wilco. Beck's version was featured on the 2004 tribute album "The Late Great Daniel Johnston: Discovered Covered," which also included versions of songs by artists including Tom Waits, the Flaming Lips, Bright Eyes, M. Ward and Mercury Rev.

Johnston's last national tour was in the fall of 2017. He played in cities across the country with different bands made up of notable musicians in each city, including the Preservation Hall Jazz Band in New Orleans, Built to Spill in the Pacific Northwest and Fugazi in Washington, D.C.

"I just feel really privileged to have had the chance to work with him," said Gimbel, speaking from Nashville where he'd just arrived for Wednesday evening's Americana Music Awards. "I think he's one of the greatest geniuses of our time." Gimbel said he expects an Austin memorial concert for Johnston may be organized in the near future.

Austin bassist and producer Brian Beattie, who met Johnston in the 1980s when he and McCarty performed Johnston's songs in Glass Eye, recorded Johnston many times over the decades. He has been working in recent years on recordings he'd made with Johnston that have not yet been released.

"Everyone he collaborated with felt like they were sprinkled with stardust," Beattie said Wednesday. "There was something very special about being with him."

One of Johnston's last musical performances in Austin came on his 57th birthday, when he appeared as part of the first Hi, How Are You Day at the Mohawk. Austin Mayor Steve Adler read a city resolution recognizing the day as an occasion for awareness about mental illness. The evening closed with many of those who'd performed Johnston's songs throughout the event joining him onstage for "True Love Will Find You in the End."

American-Statesman writer Joe Gross contributed to this report.

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