Jeff Davis' mother, Dolores, was strangled by Rader when she was 63, in 1991.
"The alternative," Davis says, "would have been to stick a needle in his arm, like you do to the pet that you love. And I think that'd be far too quick and far too merciful for him.
"For a consummate narcissist and sociopath like him, being locked down and alone is its own form of torture and hell, because he can't be the show, he can't be in control. He now will be nothing. He now will be controlled every move he makes, and for him, that's purgatory right here on earth.
"So, really, I think it's very fitting for him. Normally, I'm a big believer in capital punishment, but unless (the execution) were something particularly savage and prolonged and excruciating, which is not really legal, then this is the next best thing. It's psychological torture for him."
Before Rader was sentenced Thursday, family members of some of his victims had a chance to address him face-to-face in court.
Davis was among the ones who did, saying, "For the last 5,326 days, I have wondered what it would be like to confront the walking cesspool that took my mother's precious life."
Davis told Syler that "was pretty satisfying because, for once, he didn't have the control and we did have the control, and I wanted to exploit that to the fullest.