The killers' choice of victims made the case even more horrifying, Bengtson said. "It's kind of a sacred victim," the detective said. "It's someone's mother, someone's grandmother."
Police said they now have DNA matches on at least four previous Westside Rapist cases, and as they study the map of elderly women who were raped and strangled in one small area of Los Angeles, they believe Thomas will prove a match for many more.
As a full picture of the crime emerged, police drew a bead on their suspect. He seemed to fit the profile of a serial killer only in that he didn't seem anything like a serial killer.
"They brought him down here and he was very willing to talk to us," Jackson said. "We spent about four hours with him. ... We can't get into the details of the interview, that will be something that will be dealt with in the courts.
"Very pleasant, very pleasant talking with him."
Pleasant to talk to?
"He's very pleasant," Jackson said. "Very cooperative with us, answered our questions, to some degree."
The assessment was echoed by Earl Ofari Hutchinson, who worked with Thomas at the State Compensation Insurance Fund, where the accused killer was an insurance claims adjuster.
"What was always interesting about John. [He] was friendly, very affable, very outgoing, always had a smile on his face," Hutchinson said. "He was just a pleasant fellow, so much so that this was a kind of person that you wanted to talk to or you engaged in conversation about various things."
Hutchinson said only two things stood out about Thomas, who was his colleague until last year, when Hutchinson retired: the occasional e-mail he would send preaching Scripture, and his remarkably good health.
"I would say, 'John, you know you have to tell me, what is your secret?" Hutchinson said. "I have to package that and I'll buy it. I got to tell you, you don't look your age!'
"He would always say, 'It's just good living,' he'd smile, say 'Good living ... living right and thinking right.'"
Thomas was married five times. He served briefly in the Air Force in the 1950s; he worked as a social worker and as an electronics salesman in the '70s. And he was twice arrested for sexual assault, with both cases pleaded down to lesser charges.
LAPD Deputy Chief Charlie Beck is now overseeing the case.
"I've seen it again and again, that people who engage in these monstrous acts are thought of as good neighbors," Beck said. "I don't know who he is. I know he's a monster. We talk about predators all the time; you always hear cops talking about predators. Well, this is an apex predator targeting the weak, you know, with absolutely no remorse, no feeling, no compassion."
Beck knows this case better than most.
His father, George Beck, is the retired LAPD deputy chief who was in charge of the case three decades ago.
"It's quite a coincidence, isn't it?" said George Beck. "It kind of blows your mind as the kids say nowadays. ... There is a satisfaction there. I'm very happy for him, that it's happened the way that it has. And I know there are a lot of people that it's gonna be important to. The families of the victims."
Today, the LAPD cold case squad is fielding calls from across the country from grandchildren of women killed in the '70s. They are looking for justice. "It's tough to even hear the call, these stories are horrible," Jackson said.