BOSTON — The man who killed Sandra Birchmore was a Stoughton police officer, and he had been sexually exploiting her since she was a minor. That was the case a federal jury in Boston accepted on Tuesday, convicting former officer Matthew Farwell of killing Birchmore and causing the death of her unborn baby, the U.S. Attorney’s Office for the District of Massachusetts said.
Farwell, 41, of Easton, was convicted of killing a witness or victim. The jury also convicted him of causing the death of an unborn child. He is to be sentenced on Feb. 3, 2027, by Chief Judge Denise J. Casper of the U.S. District Court.
The Justice Department said Farwell killed Ms. Birchmore because he feared she would expose his sexual exploitation of her when she was a minor. He had also met her for sex while on duty as a police officer, the department said. Her unborn baby died with her. Farwell then staged the murder to look like a suicide.
“Despite Mr. Farwell’s attempt to silence Sandra Birchmore, today her story is told.”
“He now faces life in federal prison. Justice has indeed been served,” Foley said.
Ted E. Docks, the FBI’s special agent in charge in Boston, said the verdict “holds Matthew Farwell responsible for killing this young woman and her unborn child in a calculated attempt to silence her.”
The exploitation began in a youth program
Farwell joined the Stoughton force as a sworn officer on or about March 27, 2012. One of his assignments was instructing in the department’s Explorers Program, which introduces young people to careers in law enforcement. Sandra Birchmore joined the program in 2010, when she was 12 years old, and remained in it through the rest of her middle and high school years.
Farwell began sexually exploiting Ms. Birchmore when she was a minor, according to the Justice Department. The sexual contact continued into her adulthood, until her death on Feb. 1, 2021. On several occasions, Farwell engaged in sex acts with her while he was on duty.
A phone tip, angry texts and a final visit
In late 2020, Ms. Birchmore learned she was pregnant. Both she and Farwell believed he was the father. Witnesses testified that Farwell became violent with her when they discussed the pregnancy and his role in the child’s life. One witness testified that Farwell was “aggressive” toward Ms. Birchmore’s stomach while she was pregnant. Others testified that he pushed her when they fought over the pregnancy.
On Jan. 20, 2021, a caller to the Stoughton Police Department mentioned Farwell and Ms. Birchmore’s sexual relationship. Evidence at trial established that Farwell became visibly and audibly angry when he learned of the call and told the dispatcher not to discuss it with anyone. He then confronted Ms. Birchmore in angry text messages, including, “[Y]ou…told me that no one knew about us.”
Twelve days later, on Feb. 1, 2021, shortly after 9 p.m., Farwell texted Ms. Birchmore asking whether he could stop by her apartment. She answered that her door would be open. It was the last text message she ever sent.
Surveillance footage showed Farwell entering her apartment building at about 9:14 p.m. and leaving at about 9:43 p.m. A forensic examination of Ms. Birchmore’s phone found that its last recorded movement was at 9:40 p.m., while Farwell was still inside the building.
According to the evidence presented at trial, Farwell strangled Ms. Birchmore, killing her and her unborn baby, and then staged her death to look like a suicide. Less than 12 hours after the killing, he drove to a hospital to be present for the birth of his third child with his wife.
A death first ruled a suicide
Ms. Birchmore’s death was initially ruled a suicide by state authorities. In October 2023, several witnesses contacted federal authorities with information about her death. Ten months later, in August 2024, Farwell was arrested and charged federally.
The charge of killing a witness or victim carries a mandatory sentence of death or life in prison, the Justice Department said. The charge of causing the death of an unborn child carries a sentence of no less than life in prison. Assistant United States Attorneys Elizabeth Riley, Torey B. Cummings and Brian A. Fogerty prosecuted the case.