Derek Morse, 23, is on trial this week in the 2014 Lookout Valley triple homicide, but a witness said Friday Morse admitted the crime to him more that two years ago.
Morse's attorney said the witness, Michael Shavers, is a lying jailhouse snitch.
Shavers said he heard the tale from Morse in jail after his own arrest in February 2015 on a charge of shooting at his ex-girlfriend in a Waffle House parking lot.
Morse is on trial for three counts of first-degree murder in the April 2014 slayings of Caleb Boozer, John Lang and Jon Morris. His co-defendants, Skyler Allen and Shavers' younger half brother, Jacob Allison, are awaiting trial.
Prosecutors say Allison drove Morse and Allen to an RV lot on Kellys Ferry Road that night. Morse and Allen then opened fire on four men sitting outside, killing everyone except 16-year-old Matthew Callan, prosecutors say.
"What did Derek tell you happened?" Executive Assistant District Attorney Lance Pope asked Shavers on the witness stand.
Shavers took a long, gulping breath.
"That he killed three people."
Shavers said Morse told him it looked like the men were holding guns. Callan testified this week the men were shooting a pellet gun at targets that night.
"So (Derek) gets out, shoots across the top of the car," Shavers recalled Morse telling him. "Skyler gets out of the back seat, starts shooting. Everybody starts running. Mr. Lang's sitting in the lawn chair, never gets up, puts his hands up and says he never had anything to do with this.
"Derek shoots him execution-style in the head, then chases down Caleb, then comes back and shoots Jon Morris."
Shavers said Morse had dropped him off at a Lookout Valley motel three hours before the killings. He hung out with his girlfriend, he said, drinking from a bottle of Crown Royal until Morse, Allison and Allen showed up between 8 p.m. and 9 p.m.
Their behavior signaled something was wrong, Shavers said.
"My little brother kept looking out the window," Shavers said, "like he was afraid of something."
"What?" Pope asked.
"He wouldn't tell me," Shavers said.
Later that night Morse and Allison were in the room and Shavers mentioned he'd heard about the triple homicide from the news.
Morse said "he let his emotions get to him," Shavers said. But Shavers said he didn't know what his friend was talking about and didn't ask any more questions.
Morse's defense attorney, Dan Ripper, was unconvinced by that story and questioned whether Shavers tailored his testimony in hopes of lenience in his own attempted murder case.
Shavers had ample access to Morse's legal materials in the jail, Ripper said, and he had lied to authorities about Morse before.
After he was charged with attempting to shoot his ex-girlfriend, Shavers told Hamilton County deputies where they could find guns used in the triple homicide. He gave a detailed description of Morse stopping on Interstate 24, climbing a guardrail and ditching the guns behind a tree, Ripper said.
But that's not what happened, the attorney said.
"You knew exactly how the guns got there," Ripper said, "and the reason you knew is you're the one who put them there."
"Absolutely," Shavers said.
Ripper has insinuated that Shavers' clothes and hair better matched witness descriptions of one of the shooters.
Shavers never offered to help until he picked up his own criminal charges, said Ripper. And though Shavers said he wasn't there, he described for the jury a version of the slaying in which Morse used two weapons: a .22-caliber Ruger rifle, and a "machine-gun looking" .22-caliber.
Shavers' testimony introduced a fourth weapon atop three that jurors saw earlier in the week.
Pope asked Shavers several times Friday if he was at the murder scene.
"No, sir," Shavers said each time.
The trial continues Monday at 1 p.m. in Hamilton County Criminal Court before Judge Barry Steelman.
Contact staff writer Zack Peterson at firstname.lastname@example.org or 423-757-6347. Follow him on Twitter @zackpeterson918.