A federal jury in Boston found former police detective Matthew Farwell, 40, guilty on Tuesday, November 10, 2026, of the 2021 murder of Sandra Birchmore. Prosecutors stated that Farwell strangled the 23-year-old pregnant woman to prevent her from disclosing that he had sexually abused her starting when she was 15. The conviction included charges of killing a witness or victim and violating a federal law protecting unborn children.
The case originated in February 2021 when Birchmore was found dead in her suburban Boston apartment with a strap around her neck. Massachusetts State Police investigators and the state medical examiner initially concluded the death was a suicide. However, the FBI launched a new investigation in 2023 at the request of a former Stoughton Police Department deputy chief who had previously led an internal affairs probe into Farwell.
During the nearly monthlong trial, federal prosecutors argued that the initial local investigation was compromised. Investigators interviewed Farwell for 15 minutes in a parking lot, failed to collect his DNA, and only examined his phone after he had deleted text messages. Defense attorneys acknowledged that Farwell had an affair with Birchmore but maintained it began when she was 16—the age of consent in Massachusetts—and argued that she died by suicide after Farwell ended the relationship.
Expert testimony played a central role in the trial. A digital forensics expert testified that Birchmore’s phone stopped moving three minutes before security footage showed Farwell leaving her building. While a prosecution expert testified that Birchmore's injuries indicated a struggle during strangulation, a defense expert dismissed the homicide determination. Prosecutors also presented approximately 40,000 text messages, which they said showed the pair discussing sexual activity that occurred when Farwell was 27 and Birchmore was 15.
Matthew Farwell now faces a mandatory sentence of life in prison. The verdict concludes a legal process that involved a federal intervention into a case originally closed by state authorities. The trial featured testimony from approximately 50 witnesses and the presentation of 500 exhibits.
The FBI’s involvement was prompted by a tip regarding an improper relationship between a detective and a participant in a police youth program. The federal prosecution stepped in because local charges were never brought.
The Massachusetts medical examiner’s office has updated the official manner of death from suicide to undetermined following the federal probe. While a paternity test after her death revealed Farwell was not the biological father of the unborn child, the jury found him responsible for the deaths of both Birchmore and the fetus under federal law. Farwell remains in federal custody.