But in Gleason I found someone who was, in many ways, like the rest of us.
This killer loved his family and was fiercely protective of them. He talked often of his mother, who died of cancer when he was young, and of his children and how he wished he'd been a better father.
He joked with my colleagues who answered when he phoned from death row and complained about the "lousy Red Sox." He helped organize a motorcycle ride to raise money for a kid with cancer, and he took pride in the tattoos he spent years drawing on sailors, bikers and drunk coeds, and also in those that covered his own body.
We laughed about our accents, and how his Boston inflection was as distinguishable as my Appalachian twang. He signed almost every letter "Bobby from Boston" and reminisced about growing up in nearby Lowell, Mass.
As his execution neared, Gleason returned to Lowell in his dreams. He said he wished he'd gone back there one last time before getting locked up.
He was self-deprecating, sarcastic and always ready with a joke at an inappropriate time. He once quipped during court proceedings, "Even Ray Charles can see that, your honor."
After killing Cooper, he wrote to tell me about it and included a drawing of a man peeking over a prison wall saying, "Here we go again." Inside, he signed it "The new and improved Boston Strangler." He didn't laugh, though, when I put that in my story. It was one of several times the killer and the reporter didn't see eye to eye.
Still, it's difficult to reconcile the guy who fretted over pictures of oil-drenched pelicans after the Gulf oil spill with the one who could kill so easily that he once likened it to grabbing a beer from the refrigerator.
Gleason was adamant that he had no remorse for the lives he'd taken. He believed that before you killed a person, you'd better be able to live with what it will do to their mothers, their kids and other loved ones. If you can't live with that, you have no business killing, he said.
He once asked why I stuck with him and his story for so long, writing to him and taking his calls when most others had long tired of him. It was my job, I told him, adding that I'd stick around through his execution. Plus, I told him, he was quite fascinating.
So on Wednesday I was there again, this time to tell the world his punishment had been carried out.
And I was there to say goodbye.
Can I call Bobby Gleason a friend? As a reporter I'm not sure I should. After all, we're taught that you go into every story with an open mind, that you keep your feelings and beliefs from interfering. And this was a murderer, a man who not only took life but took it more than once — and was well aware of what he was doing.
This is real life, though, with all the grays between the black and the white of evil and good. There's simply no way to spend that much time interacting with someone, anyone — to learn about them and their fears and their history — and not gradually begin to see them as more than just a cold killer identified by a number.
I do know one thing: I may eventually forget Prisoner No. 1059266. But I doubt I'll ever forget Bobby Gleason.
Dena Potter, AP's news editor for Virginia and West Virginia, has covered law enforcement in Virginia since 2008.