FARMINGTON — Police Sgt. Michael Adcock had a hunch, one that led to the arrest of a Massachusetts man police say killed 81-year-old Grace Burton in her Fairbanks Road apartment in June.

Juan A. Contreras, 27, was arrested Thursday in Waltham, Mass. He made an initial appearance in court there Friday where he waived extradition, Maine State Police Lt. Brian McDonough said Friday during a news conference at the Farmington Police Department.

Contreras was expected to leave Massachusetts on Friday afternoon and be back in Farmington, housed at the Franklin County Detention Center on Friday night. He is expected to be arraigned in Farmington on Monday, police said.

Contreras is to be charged with murder once he is returned to Maine, Maine State Police spokesman Stephen McCausland said.

McDonough credited Adcock for acting on his hunch and making the connection.

Police would not elaborate on what type of confrontation Adcock previously had with Contreras but said Adcock realized this week that he was no longer in the area. He apparently moved back to Massachusetts after the slaying. Contreras does not have a criminal history, according to police.

Contreras was living on Pillsbury Lane, off Fairbanks Road, a short lane of trailers less than a quarter-mile from the Margaret Chase Smith Apartments on Fairbanks Road where Burton lived.

He advertised himself as a professional dog sitter and housekeeper while living in Farmington over the summer. Contreras had family living in the area, but no friends or family reported him missing, Farmington Police Chief Jack Peck said.

State police followed up on the hunch immediately. They interviewed Contreras in Massachusetts where he agreed to provide a DNA sample.

The DNA sample taken Wednesday was what police were looking for after talking with “tons of people and canvassing the neighborhood” and collecting numerous DNA samples over the past five months, McDonough said.

He also credited Burton, who provided details about her attacker before she died. After seeing Contreras’ photo, “her description was accurate. It was remarkable,” he said.

Burton called 911 after she was attacked, police said. They believe she cut her attacker, causing him to bleed and leave crucial DNA evidence in the apartment.

Although police canvassed the neighborhood, Contreras evaded police after the murder and was not interviewed at the time, McDonough said.

He met with family members on Wednesday. They were frustrated that the investigation was taking so long, he said. He thanked the family Friday for their effort and the cooperation they provided during the investigation.

Following the news of Coutreras’ arrest, the community awoke Friday to “a renewed sense of safety in their homes,” Chief Peck said. “The community came together, helped us and worked with us.”

The arrest was “an answer to prayer, that’s all I can say. It’s wonderful news,” Lois Seamon said. Seamon and Burton were best friends. Their friendship extended from childhood through their senior years.

After years of being away and moving back to Farmington, Burton reached out and brought together several classmates of the Farmington High School Class of 1947 for regular visits, said Audrey Bergeron of Farmington.

“We played cards and had a good time,” she said. The group continues to meet regularly for lunch. “We miss her terribly. She was a great person. It’s a relief to know he’s been caught for this heinous crime.”

McDonough was also appreciative of the local law enforcement agencies that worked along with state police on the investigation.

“The agencies all worked together in Franklin County. Farmington Police Department was outstanding,” he said, calling the effort “unique.”

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