Ex-police detective guilty of killing pregnant lover to hide sex abuse allegations

Supporters of Sandra Birchmore stand outside the Moakley Courthouse on October 16, 2025. (Photo by David L. Ryan/The Boston Globe via Getty Images)

The Details

The Brief

Former police detective Matthew Farwell was convicted of murder Tuesday in a federal court and faces a life sentence.

Farwell, 40, killed Sandra Birchmore in 2021 after police were tipped to a relationship between them that began when she was 15.

Farwell was tried in federal court because local investigators, some of whom knew the defendant personally, had closed the case.

The former police detective who killed a pregnant Massachusetts woman to hide an affair that started when she was 15 faces a mandatory life sentence after being convicted of her murder.

Big picture view

Matthew Farwell was found guilty in federal court of killing Sandra Birchmore, who was 23 at the time, less than two weeks after the Boston Police Department was alerted to an improper relationship between the pair.

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Dig deeper

Following her 2021 death, Farwell, 40, had tried to make it look like she took her own life and Massachusetts State Police ruled her death a suicide. Two years later, the FBI looked into the case and determined she was murdered. Federal prosecutors accused state police of not following up on leads and closing the case too soon.

What they're saying

"Justice requires persistence, not deference, not convenience, and certainly not the protection of those who wear the badge and misuse their authority," Ted Docks, the special agent in charge of the FBI’s Boston office, said at a news conference after the verdict. "No badge, no title, no position places anyone above the law."

The other side

Farwell’s defense attorneys denied he committed the murder and told the court Birchmore was 16 at the time of the affair, which is over the Massachusetts age of consent. They claimed that she had killed herself after Farwell went to her apartment to break up with her. The FBI investigation, however, revealed more than 40,000 texts between them, some of which confirmed that their relationship began when she was 15 and Farwell was 27.

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Farwell met Birchmore when she was involved in a Stoughton Police Department youth program, prosecutors said. She died on Feb. 1, 2021, and was found slumped on her apartment floor with a strap around her neck.

The Massachusetts State Police investigation included law enforcement officials who had personal connections to Farwell, and Assistant U.S. Attorney Brian Fogerty described the victim as a "troubled girl who killed herself," and said there was nothing suspicious about her death.

The FBI began reviewing the case in 2023 after being contacted by the internal affairs investigator who had been looking into the tip about Farwell and Birchmore’s relationship.

The backstory

The text messages reviewed by federal investigators found that Birchmore had pushed Farwell to impregnate her and threatened to tell his wife about the affair.

Ones sent in late 2020, after Birchmore became pregnant, discussed what role Farwell would play in the unborn child’s future. A paternity test conducted after Birchmore’s death determined that Farwell was not the father.

The Source

Information for this article was taken from The Associated Press. This story was reported from Orlando, Florida.