They called questioning his mental state "a red herring."
"We wasted a lot of time hearing from a hell of a lot of expensive doctors we didn't need to hear from. God knows we heard from too many doctors," juror Mike Castellon said.
The jurors called the various confessions by Hernandez, some of them recorded on video and played repeatedly during the four-month trial, "very reliable."
"He never unrepented, he never denied ever that he didn't kill this boy," Castellon said. "Never once did he say he didn't kill this boy."
The jurors took nine days to convict Hernandez.
"We all had different things that we were concerned about or things that we felt very sure about, some people. And other people didn't feel sure at all about," juror Cateryn Kiernan said.
WEB EXTRA: Watch the full 13-minute interview with the jurors:
The jurors eliminated Jose Ramos, the longtime prime suspect, as the result of spaghetti thrown at the wall.
"He was Hannibal Lecter and he fed her a line for the next 30 years of her life. He didn't do it," Catellon said. "The FBI abandoned it, he never confessed to it, and on and on and on. I give them credit for trying to throw that on the wall. We did spend a lot of time on that."
The jurors would not talk about the split.
"We invoked the Vegas rule," juror Tommy Hoschied said.
But after watching the videotaped confession "for the hundredth time" Tuesday morning, they voted not to convict Hernandez of intentional murder.
"I actually made a list of things that spelled out intent, things that spelled out he didn't intend to do it," an unidentified juror said. "As a group we decided there was enough grey area that we could not convict him of that."
The juror added that it wasn't a clear-cut case.
"It did take nine days or eight and a half days to get to those two. We had to look at the whole thing. We had to take the case as a whole. You can't just focus on one piece of what you consider reasonable doubt."