The US singer and songwriter who was the subject of the Oscar-winning documentary Searching for Sugarman has passed away in Detroit.

“It is with great sadness that we at Sugarman.org announce that Sixto Diaz Rodriguez has passed away,” a statement posted on his website on Tuesday said, without providing a cause of death.

His death in Detroit, Michigan in the United States was confirmed on Wednesday by his granddaughter, Amanda Kennedy.

Rodriguez’s albums flopped in the US in the 1970s, but – unknown to him – he later became a star in South Africa, where his songs protesting the Vietnam War, social mores, the abuse of women and racial inequality became hits.

Swedish filmmaker Malik Bendjelloul’s documentary Searching for Sugar Man presented Rodriguez to a much larger audience. The film tells of two South Africans’ mission to seek out the fate of their musical hero. It won the Academy Award for best documentary in 2013.

Rodriguez was “more popular than Elvis” in South Africa, Stephen “Sugar” Segerman said in 2013. The Cape Town record store owner’s nickname comes from the Rodriguez song “Sugarman”.

‘World wasn’t ready for me’

As his popularity in South Africa grew, Rodriguez lived in Detroit. But his fans in South Africa believed he also was famous in the US.

They heard stories that the musician had died dramatically: He’d shot himself in the head onstage in Moscow; he’d set himself aflame and burned to death before an audience someplace else; he’d died of a drug overdose, was in a mental institution, was incarcerated for murdering his girlfriend.

In 1996, Segerman and journalist Carl Bartholomew-Strydom set out to learn the truth. Their efforts led them to Detroit, where they found Rodriguez working on construction sites.

“It’s rock-and-roll history now. Who would-a thought?” Rodriguez told The Associated Press news agency a decade ago.

Rodriguez said he just “went back to work” after his music career fizzled, raising a family that includes three daughters and launching several unsuccessful campaigns for public office. He made a living through manual labor in Detroit.

Still, he never stopped playing his music.

“I felt I was ready for the world, but the world wasn’t ready for me,” Rodriguez said. “I feel we all have a mission – we have obligations. Those turns on the journey, different twists – life is not linear.”