Another of his jobs was looking out for pickpockets. “Everyone knew who they were,” he said, “but you couldn’t kick them out until they did something. I used to tip a big cup of soda in a guy’s lap. Either he’d get up and leave or he’d start a fight and then we could kick him out.” He was also hired to look for runaways and missing businessmen. “I guess you could say I was in the scandal-killing business,” he said.

Mr. Winslow does not look like a private investigator, which may be why he was successful. He’s small, slight and soft-spoken: the kind of person who in most books hires the P.I.

Over lunch at Big Nick’s Burger and Pizza Joint, an Upper West Side hole in the wall that used to be one of his hangouts, he said he grew up in the working-class town of Matunuck, R.I., listening to his father, a career Navy man, tell stories. (His sister, Kristine Rolofson, is a romance novelist.) Like so many young people back then, he came to New York with the notion of becoming a writer, perhaps a playwright, and fell into the private investigation business by accident, after being fired from a job as an assistant manager of a movie theater. His mistake, he says now, was that he turned in a completely honest set of books.

He didn’t publish his first novel until 1991, after a series of unlikely detours that included getting a master’s degree in African history from the University of Nebraska, a stint running safari tours in Kenya and more private investigation work, that time for high-end corporate clients. He did some industrial espionage, investigated drug use among a company’s employees and then moved on from what he calls dark work to becoming an arson expert. For three years he and his wife lived in California hotels on an expense account. “I was an overpaid migrant worker,” he said.

That first novel, “A Cool Breeze on the Underground,” written five pages a day over a couple of years, was about a graduate student who also works for a detective agency, and it was followed by four others about the same character. “I thought that was what you did, you had a series,” he said. Mr. Winslow became better known with novels like “California Fire and Life” and “The Dawn Patrol,” about a detective who is also a surfer. His breakout novel was his 13th, “Savages,” published when he was 56.