A jury has found Jay Mercier, 57, guilty of murdering Rita St. Peter, 20, in 1980. Mercier was considered the prime suspect in 1980, but the forensic technology needed to process the evidence police had, didn’t exist at the time. The evidence, including bodily fluids taken from St. Peter and tire tracks left at the crime scene languished in an evidence locker for more than three decades. Police re-interviewed Mercier in 2010, who claimed to never have met Rita St. Peter. Mercier threw a cigarette butt on the ground during that interview, and police obtained a DNA profile from that. During the trial, Mercier’s attorney did admit to the jury that Mercier lied to investigators about not knowing St. Peter and admitted that Mercier had sex with her. Prosecutors say Mercier beat St. Peter to death and dumped her body along a dirt road in North Anson in July 1980. Jurors deliberated for nearly 3 hours Thursday afternoon before finding Mercier guilty of murder.