An amended death certificate lists asphyxia as the cause of Sandra Birchmore’s death but leaves its manner undetermined, as former Stoughton police detective Matthew Farwell stands trial on a federal charge tied to her killing.
Massachusetts revised the certificate in April 2026, The Boston Globe and WBUR reported. Its cause entry says asphyxia; its manner entry is undetermined. A spokesperson for the Massachusetts Office of the Chief Medical Examiner (OCME) told The Boston Globe that examiners may reconsider a determination if later information changes what was available to them. A Federal Bureau of Investigation (FBI) detention affidavit says an OCME pathologist initially ruled Birchmore’s death a suicide in early May 2021.
A federal grand jury charged Farwell with killing a witness or victim, alleging he killed Birchmore on or about Feb. 1, 2021, so information about possible federal offenses would not reach law enforcement. Farwell has pleaded not guilty.
The superseding indictment, filed Oct. 28, 2025, added a count alleging the killing caused the death of Birchmore’s unborn son; it says she was eight to 10 weeks pregnant. The filing says Birchmore was 12 when she entered Stoughton’s Police Explorers program in 2010. It says Farwell joined the Stoughton Police Department and became an instructor in 2012. Prosecutors allege he used his position to groom and sexually abuse Birchmore, beginning before she turned 16 and continuing until around 2021.
The defense’s account is that Birchmore took her own life after Farwell’s visit to end their relationship. WBUR and Boston 25 News reported that prosecution witnesses included a medical examiner who amended the death certificate and an expert who testified Birchmore was strangled; the defense challenged that evidence.
Boston 25 News reported that prosecutors rested Wednesday, Oct. 28, and defense lawyers called forensic psychiatrist Dr. Melisa Piasecki Friday, Oct. 30. The outlet said the jury had not returned a verdict as of its report.
