MORE than two decades after four girls went missing in the Texas Killing Fields, the psychopath behind the murders has made a confession.

William Lewis Reece was connected by DNA to one of the murders but confessed to three more in 2015. The girls he killed were 19-year-old Tiffany Johnston, 12-year-old Laura Smither, 17-year-old Jessica Cain, and 20-year-old Kelli Ann Cox.

In his chilling interview with police, Reece described the details of the murders after holding it in for decades.

“I started cussing her, I think I pushed her. That’s when she hit me with the Coke,” he said about Cox.

“And then I slapped her. And then it was over.”

Reece also told investigators that “she fought back,”

When asked about what happened next, Reece explained how he killed her.

“And then I grab her around the throat, and I choke her.”

Mary Ellen O’Toole, a retired FBI profiler, was tasked by 48 Hours to study Reece’s case and what gave him the desire to confess.

Read Related Also: Indian judge who ordered Brit mum to be hanged for murdering husband in front of son claims she deserved ‘rare’ penalty

“I’ve not assessed him, not met him … but looking at his cases, looking at his behavior … I would say in my opinion that he manifests traits of psychopathy,” she said.

“What’s the worst thing that you can do to someone that has a tendency to love exciting, challenging, stimulating things? You put him in an environment like prison where they got bored.”

“These detectives recognized that. So, when you offer them the opportunity to come out … and assist law enforcement, they’re gonna jump at that.”

Once police were able to get Reece talking after decades in prison, he wanted to pour it all out. He assured investigators that he was complying completely.

“Ya’ll wanted the truth so I’m telling you the truth,” he said.

“I’m doing this of my own free will.”

While it was a major relief to get a confession from Reece, his stories have raised even more concern over the Texas Killing Fields.

Since the 1970s, more than 30 women have disappeared from the 50-mile length of Interstate 45 near the Killing Fields. While some were discovered to be murdered, many were never seen again.

There is a level of concern that Reece could be responsible for more killings in the area and hasn’t let that information out yet.

48 Hours on CBS will document the final chapter of this horrific case at 9pm on Saturday.