SKOWHEGAN, Maine — Maine State Police Crime Lab investigators and scientists on Monday detailed DNA evidence that led to the arrest of Jay A. Mercier 32 years after he allegedly killed a 20-year-old woman and left her bloody, beaten body on a dirt road.
Mercier, 57, of Industry is accused of beating Anson resident Rita St. Peter to death and then running her over in his pickup truck in July 1980, according to the state’s charges.
Past and present employees of the Maine State Police Crime Lab testified Monday at Mercier’s murder trial about the lab’s testing for sperm and skin samples on St. Peter’s clothing and body.
Initial attempts by the crime lab’s serologist in 1980 to identify the blood type of the perpetrator proved to be little help to the investigation. DNA was not well understood at the time and wouldn’t prove to be an effective piece of evidence in solving crimes until two decades later.
After revisiting evidence in 2009, investigators found semen in a rectal swab taken from St. Peter after she was found dead. They also found semen in samples taken from St. Peter’s underwear.
Todd Settlemeyer, Steve Shargo and Kathy MacMillan of the crime lab said the lab began taking another look at the evidence in the St. Peter cold case after 2005.
St. Peter’s clothing and oral, rectal and vaginal swabs were tested again. This time, testing produced some information, which was paired against “known” samples from Mercier and eight to 10 other individuals police had investigated.
Samples taken from St. Peter’s underwear revealed DNA from two men, neither of whom was Mercier, and neither of whom was among the eight to 10 other men police had taken samples from, according to MacMillan.
The re-examination of the rectal swab produced a stronger result, according to MacMillan. Mercier’s DNA sample matched the sample taken from the rectal swab. The probability of the DNA belonging to someone other than Mercier is “one in trillions,” MacMillan said.
During Shargo’s testimony, the forensic chemist referred to swabs, clothing stains and samples as being evidence of sexual assault.
“You have no information about an assault — a sexual assault,” defense attorney John Alsop of Skowhegan said in reply, adding that the swabs and clothing samples indicated only that sexual activity had taken place.
In his opening argument last week, Assistant Attorney General Andrew Benson told jurors that modern forensics had helped solve what had been classified a “cold case.” He said that DNA from a cigarette smoked by Mercier during a police interview about two years ago, as well as an oral swab taken in 2011, matched DNA found on St. Peter’s body. He also said the tire tracks photographed at the scene matched those on Mercier’s truck.
Dr. Margaret Greenwald, Maine’s chief medical examiner, opened Monday’s proceedings by testifying that St. Peter likely was killed by repeated strikes to the head and chest with something heavy.
“The injuries to the head were most likely inflicted by a long, heavy object,” Greenwald said.
She said that before the trial she had reviewed the report of her predecessor, the now-retired Dr. Henry Ryan, as well as photographs of the autopsy. Based on the photographs, she said, the injuries to St. Peter’s head and torso were not consistent with being run over by a vehicle.
Greenwald took over as medical examiner in 1997 after Ryan retired.
Greenwald noted bruises and abrasions on St. Peter’s body. She also said the photographs didn’t reveal any trauma to St. Peter’s genitals, but that the state of her clothing at the time she was found was “certainly suggestive of some kind of assault.”
Paul Stewart, a state police officer who retired in 2006 after 32 years, was a detective at the time of the St. Peter murder. He said he visited the crime scene and drew a diagram of tire tracks around St. Peter’s body before going into town to conduct interviews.
Those interviews eventually led police to Mercier, whom Stewart interviewed three times during his four months on the case. During the first interview on July 6, 1980, Mercier talked to Stewart for three hours.
During that interview, Mercier told Stewart he had spent the afternoon of July 4 drinking beer and cutting wood alone. He said he consumed three 6-packs of Budweiser before going to the parking lot of a Madison bank around 10:30 p.m. to talk with friends.
Mercier also said he made five trips behind the school in Anson to “relieve himself” before going home between 12:30 and 1 a.m. on July 5. A little more than 12 hours later, St. Peter was found dead.
Mercier sat stoic through most of Monday morning’s testimony, his hands clasped in his lap. He occasionally reached up to fidget with his tie and beard or adjust his glasses, but was never seen speaking to his attorneys, Alsop and John Martin, also of Skowhegan.
Court recessed early, shortly after 2 p.m. Monday, because of state witness scheduling conflicts. The trial will resume at 8:15 a.m. Tuesday at Somerset County Superior Court.
The Somerset County grand jury indicted Mercier on a murder charge on Sept. 16, 2011. He was arrested at his home on Sept. 28 and pleaded not guilty on Oct. 6. Mercier was denied bail in January and has been held at the Somerset County Jail in East Madison since his arrest.