A recipe for acclaim, lots of dollars and a big Broadway hit: take an obscure criminal, investigate his life story, sell it to a tolerant, 1990s audience and surround the entire project with a moral conundrum about the possibility of redemption. Easy? Well, perhaps, but it helps if you're Paul Simon on your way to your first Broadway musical (no off-Broadway run to ensure the appeal of the material necessary). Simon's stage show The Capeman was seven years in the making, and has been billed as 'a kind of narrative, told in common language, about ordinary people'. It features almost 40 new songs, from which 13 have been distilled and issued as Songs from the Capeman, his first record since the lauded Rhythm of the Saints in 1990. The story behind the work is one of urban violence and newspaper mythology. The scene is New York City, summer, 1959. Central to the tale is Salvador Agron, an immigrant, a gang member - and a double killer. 'Agron wore a black cape with a red lining; he was part of an Upper West Side outfit called the Vampires, and one night in August they went to a rumble in a park with a gang called the Norsemen, from Hell's Kitchen,' says Simon. What happened next became banner headlines. 'The Norsemen didn't show', continues Simon, 'but because the Vampires were pumped up and ready to fight, they singled out a few innocent kids and attacked them.' Two were killed. 'The people in the park said there was a tall Puerto Rican kid wearing a black cape, and a little guy with an umbrella. So the newspapers called them the Capeman and the Umbrella Man,' says Simon. The manhunt which followed was one of the most intensive in New York history, involving 1,400 police and lasting almost a week. 'They caught Agron and Tony Hernandez - the Umbrella Man - in the South Bronx. The entire city was horrified; it was a year when there was a lot of teen violence, and this was an egregious example of how things had got out of control. 'When Agron, who was only 16 - the kids who were killed were only 16 too, babies - when he was captured, he said: 'I don't care if I burn. My mother could watch.' He was apparently remorseless, so he became the symbol of evil in the city. 'There was a death penalty then and he was sentenced to the electric chair . . . the youngest ever in New York State. He was on death row for three years, then Governor Rockefeller commuted his sentence.' So The Capeman was a tabloid tale of juvenile delinquen cy. How did it be come a musi cal? 'I don't know what drew me to the material,' Simon admits. 'I remembered the events - everyone in New York at the time remembers the Capeman. But the idea of turning it into a musical came to me in 1988, after Graceland. 'The possible juxtaposition struck me - doo-wop and Latin rhythms, which make an evocative combination. So I began researching the story, reading the newspaper accounts and seeing people who either knew Sal or who were of his generation.' Simon's investigations led to some distressing moments. 'I talked to the prison chaplain at Sing Sing, to Sal's sister and his mother, and I interviewed a representative of a group called Parents of Murdered Children of New York State. 'That was a very painful experience and made me consider dropping the whole project.' But Simon persevered, and also discovered a new and challenging method of working. 'The difference between The Capeman and everything else I've done is that I collaborated on songs for the first time,' he says. 'My usual approach to songwriting is to put down whatever is on my mind. The character speaking is usually me. Suddenly, I was writing for several characters, sometimes in a single song, and I needed a different point of view.' That came from Nobel prize-winning poet Derek Walcott, whose Caribbean roots were invaluable in telling the story of a displaced Puerto Rican family. 'I have loved Derek Walcott's work for years,' reveals Simon. 'He was my only choice for a collaborator. 'It was a little intimidating at first, but we settled quickly into a good working relationship. We're co-lyricists.' And what of Salvador Agron? While The Capeman saga faded from the papers after his conviction, the killer 'had a long journey through the prison system', says Simon, 'serving 20 years before being released in 1979. 'Not surprisingly, he found religion on death row, but also evolved from a barely literate wild boy into a thinking, politicised writer and activist. He wrote his life story - and it was only natural to use him as a narrator here.' Simon's show and album begin as Agron is released from prison and starts to wander through his memories as he heads for his mother's house. Agron himself enjoyed seven years of freedom before dying of natural causes at 43. And while it may seem ironic that New York's former bete noire should now become a Broadway icon, for Simon his story is also a facade for deep questions of morality. 'There is a strong political and sociological element to this work, but that's not what it's about,' he adds. 'At its core is a question about the possibility of redemption. If someone has committed an act as terrible as a double murder, who decides whether they can be redeemed? 'Does society decide? Can the criminal look into himself and find forgiveness? Or is it impossible to pay the penalty for sin and be cleansed?'