It’s day three in the trial of an Industry man accused of killing a woman and dumping her body in North Anson more than thirty years ago.56-year-old Jay Mercier is charged with killing 20-year-old Rita St. Peter in July of 1980.Monday, one of the investigators who interviewed Mercier thirty years ago took the stand.According to retired Detective Paul Stuart, Mercier told him he was drunk at home the night Rita St. Peter was killed.Stuart said Mercier also tokd him it had been two weeks since he’d been in the Depot bar in Madison where St. Peter was last seen leaving, highly intoxicated. Witnesses who testified Friday told the jury Mercier was actually in the Depot bar the same night St. Peter killed.One of those witnesses told the jury St. Peter was visibly drunk when she left the bar and she saw Mercier follow St. Peter in his truck.The prosecution also laid out their DNA evidence Monday. Taking the stand were a pair of forensic chemists and DNA analyst Kathy MacMillan, who all work at the Maine State Police Crime Lab in Augusta.MacMillan told the jury that DNA taken from sperm cells found on St. Peter matched Jay Mercier’s DNA profile.MacMillan said she found two DNA profiles from bodily fluids taken from St. Peter during her autopsy back in 1980. One of those profiles belonged to the victim, while the other belonged to an unknown male subject.State Police Detective Bryant Jacques interviewed Mercier back in 2010 and collected a cigarette butt Mercier had thrown on the ground during that questioning. DNA taken from that cigarette butt matched the DNA profile of the unknown male subject and provided police with enough probable cause for a warrant, forcing Mercier to submit to a cheek swab for a DNA sample.The DNA from the swab was a match to the DNA left in the body of Rita St. Peter. MacMillan told the jury the chance that the DNA is anyone other than Jay Mercier is one in a trillion.During cross examination, MacMillan testified that DNA from two other unidentified people was also found during an examination of the underwear St. Peter was wearing when police found her body. Mercier had repeatedly told police he had never met Rita St. Peter.The trial continues Tuesday and is expected to wrap up sometime this week.