Maryanne Vollers, author of Ghosts of Mississippi and Ice Bound and unnamed co-author of Hillary Clinton's Living History, explores the case of bomber Eric Robert Rudolph (Lone Wolf).

What attracted you to Rudolph's story?

First I thought I was going to write about American outlaws, with Rudolph as point of departure, because when the main character is going to trial, you never get cooperation. It was a federal terrorism case, so I was not getting anywhere with anyone. Then, everything turned around: Rudolph pled guilty and started to write to me. Everybody was talking to me: the lawyers, the U.S. attorney, everybody.

Did you come to any conclusions about why he became an outlaw?

It's difficult to put him in a category. The human heart and the motivations of such extreme behavior can be explained only up to a point. Rudolph has what the experts call an "encapsulated pathology"—he can be very normal. But sometimes sickness overwhelms him. Bringing up abortion, or government, it's almost like he has a seizure.

You've been a journalist for more than 30 years. How has investigative reporting changed since you started?

It's different now because of Amazon and self-publishing and all this. A lot of the people involved in high-profile situations like this think: "Well, I'm going to write my own book." Truman Capote's In Cold Blood is the gold standard for the form. If Capote arrived in Kansas today, 40 years later, he would find that the rights of the surviving family members had already been acquired, there were book deals in the works—and he'd have to go home to New York and write about his dog.

Capote got famously attached to one of the criminals in his book. Have you ever had trouble keeping a professional distance?

It's a delicate dance, especially when the subject is a charismatic murderer. Because of Rudolph's personality, it was easy never to promise him anything except to listen to him and try to understand him. I began with the hope that I'd tell his story objectively, but it's impossible to write the book without taking a moral stand.

You have written about Jerri Nielsen and Byron De La Beckwith and Hillary Clinton, as well as Rudolph and others. What's the connection?

My subject matter, when you look at it, is the heroes and villains in American history. When I was 14 my brother committed suicide—he was 24 and a Vietnam vet. I think that has something to do with my career, which has been an exploration of the inexplicable. I'm always trying to find a narrative to a story that makes no sense.