By Poppy Harlow
(CNN) - Imagine becoming more popular than Elvis Presley or the Rolling Stones, but not finding out about it until decades later.
That's the story of musician Sixto Rodriguez and the subject of a documentary on his life called Searching for Sugar Man.
Sixto Rodriguez is a Dylan-esque Detroit native who tried his hand at rock history in the 70s.
"When we walked in and heard the songs he was singing, and what he was writing. We had to record him. We had to make a deal for him, he's great. We said, this is it," said co-producer Mike Theodore.
But it wasn't. His albums flopped in the United States. Somehow though his first album, Cold Fact, made it halfway around the world and became a massive hit.
"In South Africa, he was in the pantheon of rock gods," said Malik Bendjelloul, Director of Searching for Sugarman.
"To us, it was one of the most famous records of all time," said Stephen Segerman, owner of Mabu Vinyl in Cape Town.
The soundtrack of the anti-apartheid movement was fueling a revolution.
But at home in Detroit, Rodriguez had no idea. He had given up his music career four decades ago.
[Reporter]: "You used to play right across the street there right?"
"I played a lot of places in Detroit," said Rodriguez.
Unaware of his fame abroad and getting no royalties, Rodriguez lived on little, and raised his daughters doing demolition work.
"I'm not a stranger to hard work," said Rodriguez.
He made failed bids for mayor, city council, and state representative.
[Reporter]: "You call yourself a musical political."
"A musical political, yeah. I don't see how anybody can't be and is not political," he said.
Then, at 57, he was re-discovered by a South African music journalist and a record store owner who found clues in his lyrics.
They brought him to South Africa and he played to thousands of adoring fans.
"He's on stage and the crowd is just going wild and they're singing and they're crying," said his daughter, Sandra Rodriguez.
"It brings you to tears to see something like that happen to someone," said his other daughter, Regan Rodriguez.
"Well it was, it was epic," said Rodriguez.
[Reporter]: "Do you not think that your story is exceptional beyond belief?"
"Oh it's pretty wild, the story. I'm a lucky man to be so fortunate at this late date," said Rodriguez.
Bendjelloul tells it in his documentary Searching for Sugar Man.
"A man who lives his whole life in Detroit working as a construction worker, really hard manual labor, without knowing that at the very same time he's more famous than Elvis Presley in another part of the world. I thought it was the most beautiful story I've ever heard in my life," said Bendjelloul.
A beautiful story, but also a mystery. Where were all the royalties?
"I don't know. I don't know. I do think it's an important question because the reason why Rodriguez didn't know he was famous for 30 years was that he didn't get royalties," said Bendjelloul.
[Reporter]: "Do you ever feel gypped?"
"Well, no not in that sense of, hate is too strong an emotion to waste on someone you don't like," said Rodriguez.
[Reporter]: "Do you want the fame and the fortune?"
"Well fame is fleeting, you know," he said.
Now 70, Rodriguez may finally get his due.
[Reporter]: "Do you ever pinch yourself and ask, is this real?"
"It's certainly a different life. You know, it's certainly not what it was," said Rodriguez.