Steve Harwell, Former Lead Singer of Smash Mouth, Dead of Liver Failure at 56

The band's manager previously confirmed to PEOPLE that Harwell was in "hospice care" with only "a short time left to live"

Steve Harwell, the former frontman of Smash Mouth, has died. He was 56.

The singer died of liver failure on Monday, Sept. 4 at his home in Boise, Idaho, the band's manager Robert Hayes confirms to PEOPLE.

Smash Mouth paid tribute to their former bandmate via an Instagram post shortly after his death.

"Steve Harwell was a true American Original. A larger than life character who shot up into the sky like a Roman candle. Steve should be remembered for his unwavering focus and impassioned determination to reach the heights of pop stardom," they wrote.

"And the fact that he achieved this near-impossible goal with very limited musical experience makes his accomplishments all the more remarkable. His only tools were his irrepressible charm and charisma, his fearlessly reckless ambition, and his king-size cajones."

The band continued, "Steve lived a 100% full-throttle life. Burning brightly across the universe before burning out. Good night Heevo Veev. Rest in peace knowing you aimed for the stars, and magically hit your target."

On Sunday, Hayes had said Harwell was "resting at home being cared for by his fiancée and hospice care" with only "a short time left to live."

TMZ was first to report that the singer was in the final stage of liver failure after previously undergoing treatment for alcohol abuse at a hospital.

A source close to Harwell explained to PEOPLE in 2021 that the musician had "suffered profusely" with addiction over the years, which have led to some of his medical and mental health issues.

Related: Steve Harwell Is in Hospice with Only a 'Short Time Left,' Smash Mouth Manager Says

“Even though Steve has not been with Smash Mouth for two years now, and the band continues to tour with new vocalist Zach Goode his legacy will live on through the music,” Hayes told PEOPLE on Sunday.

“With Steve, Smash Mouth has sold over 10 million albums worldwide-wide and topped the charts with two No. 1 hit singles, five Top 40 singles, three Hot 100 singles, four Billboard 200 albums and a Grammy nomination not to mention the hundreds of film and television placements and of course those musical features in Shrek.”

“Steve's iconic voice is one of the most recognizable voices from his generation. Steve loved the fans and loved to perform,” added Hayes.

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Before his time in Smash Mouth, Harwell rapped for music group F.O.S. (Freedom of Speech) and released the track “Big Black Boots.”

“Around the time we were about to put out our single, this kid Snoop Dogg came out and changed everything,” Harwell recalled in a 2017 interview with Stereo Gum. “I was at a radio convention in Las Vegas watching MC Hammer of all people, and I just looked at my manager, “I’m tired of all this hip-hop s---, I want to start an alternative rock band.’”

Harwell then formed Smash Mouth with drummer Kevin Coleman, guitarist Greg Camp and bassist Paul De Lisle in 1994.

The four went on to drop their biggest hit “All Star” in 1999, which was featured on the soundtrack in the Shrek franchise, along with their well-known cover of the Monkees’ “I’m a Believer.” They also released songs "Walkin' on the Sun," "Can't Get Enough of You Baby" and "Why Can't We Be Friends."

Along with appearances on other film and TV soundtracks, Harwell also composed “I Wan’na Be Like You (The Monkey Song)” for Disney’s The Jungle Book 2 (2003) and two songs for the 2013 children’s animated movie The Little Penguin Pororo’s Racing Adventure.

In 2006, he joined the cast of season 6 of the VH1 reality show The Surreal Life, which followed a group of celebrities living together in Glen Campbell’s Hollywood Hills mansion. He also appeared as himself in the 2001 comedy Rat Race and voiced characters in a 2003 episode of Kim Possible and a 2018 episode of We Bare Bears.

Related: Smash Mouth's Steve Harwell Taking a Brief Break from Band Due to Heart Issues

During the later years of his career, Harwell suffered from several health complications with 2013 diagnoses for cardiomyopathy and Wernicke encephalopathy.

Just a day after an October 2021 performance in New York where the singer exhibited eccentric behavior that a source later explained to PEOPLE was an “episode,” Harwell shared in a statement with PEOPLE that he would be retiring from Smash Mouth due to his mental and physical health.

"Ever since I was a kid, I dreamed of being a Rockstar performing in front of sold-out arenas and have been so fortunate to live out that dream," Harwell said at the time. "To my bandmates, it's been an honor performing with you all these years and I can't think of anyone else I would have rather gone on this wild journey with."

"To our loyal and amazing fans, thank you, all of this was possible because of you," he continued. "I've tried so hard to power through my physical and mental health issues, and to play in front of you one last time, but I just wasn't able to."

Harwell is survived by his fiancée Esther Campbell. He was also father to son Presley Scott, who died of complications from acute lymphocytic leukemia as an infant in 2001.

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