FARMINGTON, Maine — Juan Contreras walked into Franklin County Superior Court on Monday morning for his murder trial in the June 21, 2011, death of Grace Burton.

Burton, 81, who was asleep in her Farmington living room recliner at about 1 a.m. that night, told police she awoke to someone stabbing her, Assistant Attorney General Deborah Cashman said before Justice Michaela Murphy. Burton died later that morning after suffering 35 stab wounds. Someone had gained entrance to her apartment by slicing the screen on her bedroom window. She resided at the Margaret Chase Smith Apartments, 195 Fairbanks Road.

Retracing the events that led police to Contreras, 28, who moved to Massachusetts about a month after Burton’s death, Cashman said DNA samples taken from blood stains at the scene matched Contreras’ DNA.

He was arrested Nov. 17 and returned to Maine. Initially he claimed he was not responsible and was not even in Farmington at the time, she said.

But his attorneys are taking a different tack.

Farmington was left with two questions following the incident, the who and why, said attorney Christopher Berryment, who along with David Sanders, is representing Contreras.

“The who is answered. Juan caused the death,” Berryment said. “After a year and hundreds, thousands of hours of investigation, the why is still not answered.”

The defense asserts it is a case of involuntary intoxication and that Contreras smoked marijuana that he didn’t know was laced with bath salts.

While the state does not have to prove motive, it’s a matter of whether he intentionally or knowingly caused her death, Cashman said.

Contreras apparently left a downtown bar and went into Burton’s apartment through a window. He stabbed her and then went home at about 1:30 a.m. and lied to his wife about a cut on his hand, Cashman said. Contreras was living with his wife’s father, about two-tenths of a mile from Burton’s apartment.

Evidence shows no natural motive and the act was not born of a rational mind, Berryment said.

More than $3,000 in cash and 13 medications in the home were undisturbed and there was no evidence of theft, Berryment said.

The defense team describes Contreras as nonviolent. His wife, Amanda Pressey, of Farmington, said he was not violent or threatening during their two-year relationship, Berryment said.

Two bartenders will testify over the course of the trial.

At the Front Street Tavern that night Contreras was drinking and shared marijuana with another customer outside, Cashman said. The men then went to the Dugout where another bartender will testify Contreras was acting strangely and paranoid, his pupils dilated, Berryment said.

There’s reasonable doubt that he was acting rationally, he said.

About 20 members of Burton’s family and friends cried quietly or looked down as they listened to Burton’s voice while her call to 911 was played in the courtroom.

Testimonies began with Wayne Drake, then a patrol officer with Farmington Police Department, who was the first to respond, followed by officer Adam Welch from the University of Maine at Farmington Police Department.

Unable to get into the apartment, Welch kicked in the front door. They found Burton lying on the floor.

She was in and out of consciousness but was able to tell them her attacker had a small mustache and wore a baseball cap, Drake said.

State police were called as well as a tracking dog from Franklin County Sheriff’s Department. Drake found a leaf outside the bedroom window with a red-brown stain and alerted state police to it, he said.

The state also called Dr. Margaret Greenwald, Maine’s chief medical examiner to the witness stand. Greenwald, who performed an autopsy on Burton the next day, said she found multiple stab wounds to the face, chest, abdomen and extremities. She said blood and oxygen loss led to her death.

Five wounds on her hands were similar to ones that are considered defensive type wounds, she said, indicating there was a struggle.

Sgt. Scott Gosselin of the Maine State Police testified that about 10 blood drops were found on the back side of the apartment building showing the attacker taking a trail headed north. A stain was also found on the bedroom window sill.

The trial resumes at 8 a.m. Tuesday and is expected to last most of the week.