Stoughton Detective Sentenced to Life for 2021 Murder

Matthew Farwell, a former Stoughton police detective, now faces a mandatory life sentence after a federal jury convicted him of second-degree murder on Tuesday. The verdict resolves a case that began when Sandra Birchmore was found dead in her apartment in 2021, an incident initially ruled a suicide before federal investigators reclassified it as a homicide.

Prosecutors argued that Farwell killed Birchmore to stop her from revealing a sexual relationship that began when she was a teenager. The trial, which lasted nearly a month in Boston, centered on evidence suggesting Farwell staged the scene to look like self-harm. Federal officials criticized the original local investigation for closing the case too quickly and for failing to follow basic procedures, such as taking notes during Farwell’s brief 15-minute interview in a parking lot.

The jury heard from witnesses and reviewed roughly 40,000 text messages exchanged between the two. These texts documented a relationship that started when Farwell was 27 and Birchmore was 15, an age below the legal threshold for consent in Massachusetts. The messages also showed Birchmore pressuring Farwell to get her pregnant and threatening to tell his wife about their affair. A paternity test conducted after her death confirmed that another man was the biological father of the child she was carrying.

Defense attorneys acknowledged the affair but argued it began when Birchmore was 16, an age of valid consent. They contended that Birchmore had a history of suicide threats and killed herself after Farwell visited her apartment to end the relationship. A digital forensics expert testified that Birchmore’s phone stopped moving just three minutes before security cameras showed Farwell leaving her building on the night of her death.

Medical experts offered conflicting views on the cause of death. Dr. William Smock, testifying for the prosecution, stated that Birchmore was strangled with a duffel bag strap and struggled before dying. Dr. Thomas Andrew, a former chief medical examiner in New Hampshire who testified for the defense, disputed the homicide determination. The state’s medical examiner has since changed the official manner of death from suicide to undetermined.

Assistant U.S. Attorney Brian Fogarty told jurors that one state investigator found nothing suspicious in the apartment, describing Birchmore as a troubled girl who took her own life. Fogarty noted that some investigators involved in the early review had personal connections to Farwell. The federal government took over the case because local authorities had not filed criminal charges against the former detective prior to the 2023 federal investigation.