Earl Edward Devaney

Earl E. Devaney, who began his career as a Secret Service agent guarding President Richard M. Nixon and rose to become one of the American government’s most aggressive and feared internal watchdogs, died on April 15 in Boca Raton, Fla. He was 74.

His son Michael said the death, at a hospital, was caused by complications of a heart attack.

Friends and foes alike called Mr. Devaney the Big Man, and not only because he long retained the imposing heft he once yielded as a college football player.

An administrative entrepreneur, he helped build the financial-fraud arm of the Secret Service, gave real teeth to the enforcement capabilities of the Environmental Protection Agency, took down a corrupt agency within the Interior Department as its inspector general, and managed to keep the vast 2009 economic stimulus effort virtually fraud free.

Mr. Devaney had a flair for flashy cases and headline-grabbing congressional testimony, not, by his account, for their own sake or to boost his career, but for their deterrent effect.

“You can have an inspector general who lurks in the shadows,” Felicia Marcus, a fellow at Stanford University who worked with Mr. Devaney at the E.P.A., said in an interview. “He did not lurk in the shadows.”

In his office at the Interior Department he kept an alligator head with a camera hidden inside, which he had used to film a department official engage in a bribery deal while on a fishing trip in the Louisiana bayou.

“When an assistant secretary comes in and asks about it, I tell that story and they get a little unnerved,” he told The New York Times in 2009.

When he arrived at the Interior Department in 1999, many people in the leadership had never met his predecessors, nor did they need to — the typical inspector general quietly issued reports and might testify before Congress once in his or her career, but rarely did someone in that role make an active effort to squash wrongdoing or to bring transparency to government operations, two things Mr. Devaney relished doing.

“Ed was a standout because he recognized the full breadth of the responsibilities of an inspector general,” Danielle Brian, executive director of the nonpartisan Project on Government Oversight, said in an interview.