Write what you know, they say, so Robert Mulcahy wrote about the FBI.
A former FBI agent, the Oklahoma City man has penned five books about the crime-busting bureau " two of them nonfiction " including his latest novel, "The Grave."
"This is the fifth, and the last," Mulcahy said. "I'm 81 years old. The only way an author can sell a book is to have a TV show like (Bill) O'Reilly has or have some of kind of agent that's out there plugging your books. There's an awful lot of books in the market, and it's very difficult to keep selling them, so I figure I ought to quit at my age and just play golf."
While at the FBI, Mulcahy worked bank robberies for about 10 years. Before he was transferred to Oklahoma City in 1969, he was one of three agents investigating them from the Kansas City, Mo., office.
"During the '60s, there were bank burglaries almost every weekend, or at least it seemed that way," he said. "So I wanted to write a book about burglars."
The resulting novel was "Kansas City Charlie," whose agent protagonist returned for a sequel, "The Quarrel," when the wife of Mulcahy's publisher demanded one. The current "The Grave" tells a story of a PI caught in a web of lies, prostitution, drugs and murder in Oklahoma City.
But all that came after Mulcahy's first post-FBI career. After he retired in 1980, he set up shingle as a private investigator. He ran his for-hire spy shop for about 15 years, "until the computer age kinda put me out of business."
From there, he had two options: Either quit, or go to school to learn the ins and outs of computers.
"I took the easy way out," he said. "I closed up shop and got a job as a marshal over at Lincoln Park (Golf Course). That way, I got to play a lot of golf and didn't get paid for it. That was fun."
He went back to school, in a way, when he took a writing class that met weekly, which eventually spurred him to take a crack at authoring books.
His first two, "Targets of the FBI" and "FBI Family," recounted cases over his 34-year career with the bureau. The latter remains his favorite.
"I had fun writing it, because it brought back a lot of memories of cases I had worked," he said.
One of his final cases involved the arrest of scam artist Jack Vessels.
"His brother, (University of Oklahoma's) Billy Vessels, won the Heisman trophy," Mulcahy said, "but Jack was no good."