William Farwell, the twin brother of former Stoughton police officer Matthew Farwell, testified under an immunity agreement Monday in the ongoing federal trial accusing Matthew Farwell of murdering 23-year-old Sandra Birchmore. The trial, held in federal court, centers on charges that Matthew Farwell strangled Birchmore on February 1, 2021, allegedly to conceal past misconduct, including sexual abuse when Birchmore was underage and misuse of work hours to have sex with her.
During his testimony, William Farwell, also a former Stoughton police officer, confirmed that he had a consensual sexual relationship with Birchmore beginning in 2018 when she was 21 years old. He denied having any sexual contact with her while she was a minor and stated he had no knowledge of any relationship between Birchmore and his brother Matthew. William Farwell said he sought immunity to avoid charges related to having sex with Birchmore during work hours, which allegedly involved inappropriate use of his law enforcement authority. Both brothers resigned from their police positions in 2022 following an internal investigation related to the case.
Matthew Farwell has pleaded not guilty to the charges of murdering Birchmore and her unborn child. His defense maintains that Birchmore, who had a history of mental health challenges, died by suicide after ending her relationship with Matthew Farwell and fearing for her pregnancy’s viability. The case has included extensive and graphic testimony over more than two weeks, with prosecutors working to prove not only that Matthew Farwell caused Birchmore’s death but that he did so intentionally to suppress evidence of his federal crimes, including sexual abuse and fraud.
A key aspect of the trial involves conflicting medical opinions about Birchmore’s cause of death. Dr. Maria Capo Martinez, the state medical examiner who conducted the autopsy, initially ruled Birchmore’s death a suicide, a finding that contributed to local prosecutors declining to press charges in state court. However, earlier this year, she amended the death certificate to reflect an “undetermined” cause of death. Dr. Capo Martinez testified that her original determination was based on information available at the time and that additional evidence provided later, which she had not initially received, prompted her revision. She acknowledged that medical examiners rely on law enforcement agencies for investigative details and that incomplete information can impact conclusions about the manner of death.
Prosecutors suggested that critical information, including details about Birchmore’s phone activity and DNA evidence related to a strap found on her body, was not shared with the medical examiner during the initial investigation. They intend to present testimony from another medical expert who disputes the suicide ruling and supports a homicide determination.
Under cross-examination, Dr. Capo Martinez denied feeling pressured to change her findings despite heightened federal scrutiny of the case. The defense has used her initial ruling to challenge the prosecution’s allegations, while prosecutors emphasize the discrepancy to argue that Birchmore’s death was not self-inflicted.
William Farwell is expected to return to the witness stand Tuesday as the prosecution nears the conclusion of its case, with the defense anticipated to begin presenting evidence shortly thereafter. The trial continues to explore complex issues surrounding abuse of authority, consent, and the circumstances of Birchmore’s death.