Fellow officer says she was concerned by Matthew Farwell's demeanor days before Sandra Birchmore's death

A woman who worked with Matthew Farwell at the Stoughton Police Department testified Wednesday at his federal trial in Massachusetts that she was concerned about his demeanor just days before Sandra Birchmore was found dead.

Sandra Barrett, a veteran Stoughton police detective, took the stand as Farwell is standing trial accused of killing 23-year-old Sandra Birchmore and her unborn baby in 2021.

Barrett has worked at the Stoughton Police Department since 2001 and became a detective in 2016. Farwell became a detective about two years after her.

"We were very good friends," said Barrett, adding the two would spend time together outside of work, and she knew his wife and children.

Barrett also said she knew Sandra Birchmore from around town, adding that Birchmore was often where police officers were.

"She was nice. I felt that she was a little immature," Barrett said. "Even when I spoke to her in her older years, I felt like I was talking with a juvenile. I felt she was just a little immature. Socially awkward."

The prosecutor asked Barrett if she ever believed Birchmore was in a sexual relationship with Farwell before her death. Barrett said she did not.

In January 2021, Barrett said Farwell's demeanor changed. She testified that he seemed agitated, stressed, and was frequently going outside to take phone calls. Barrett said she attempted to address her concerns with Farwell at the end of that month while at a restaurant.

"I asked the defendant if everything was okay," Barrett said. "He explained to me that he was having problems with a female partner in his life, someone other than his wife."

Barrett said Farwell told her the female was threatening to tell his wife.

"He told me that he was fine and that he believed the problem was going to take care of itself," Barrett said.

Barrett testified that a day or two after the conversation, she learned Birchmore had died.

According to Barrett, Massachusetts State Police did not interview her after Birchmore's death.

Police originally ruled Birchmore's death a suicide. Later, federal investigators arrested Farwell and accused him of killing Birchmore then attempting to stage the scene as a suicide.

On cross-examination, Barrett was asked if she was surprised to initially learn Birchmore had died by suicide.

"I didn't have much feeling about it either way," she said.

Farwell faces a mandatory sentence of life in prison if convicted. He has pleaded not guilty to charges of killing a witness or victim and causing the death of an unborn child.