This article was originally published on www.nbcnews.com by Elisha Fieldstadt on October 19, 2018

A Pennsylvania man serving a life sentence for murdering his wife and stepdaughter has confessed to a two-decade-old murder and is a suspect in more killings, authorities said Thursday.

Regis Brown, 59, confessed in March to the 1988 killing of Bryce Tompkins in Lawrence County, District Attorney Joshua Lamancusa said Thursday during a news conference. The confession came shortly after he was arrested in the killings of his wife and stepdaughter.

Tompkins’ body was found in a creek in 1988, Lamancusa said. He had been shot two times in the back with a .38-caliber pistol.

Brown told police in March that he and a man named Paul Ayersman killed Tompkins because he had witnessed them steal a .38-caliber Smith & Wesson revolver.

Investigators have since tried to find the gun, which Brown said he buried, but they were unsuccessful. Several witnesses, however, told police that Brown and Ayersman did murder Tompkins, Lamancusa said. Ayersman has since died.

Brown has been charged with homicide, aggravated assault and intimidation of a witness in that case, and Pennsylvania State Trooper Trooper Joe Vascetti said more charges in separate cases could be forthcoming.

“He’s either been arrested for, or confessed to, or is a strong suspect in eight homicides right now,” Vascetti said Thursday. He said most of the murders occurred in the northwestern part of Pennsylvania from 1986 to as recently as 2016.

“He has a checkered past. He’s a violent offender,” Vascetti said, adding that Brown was involved with the Outlaw Motorcycle Club, a violent biker gang.

Brown is cooperating with investigators, Vascetti said.