Updated September 12, 2026. This page is the standing record of United States v. Farwell, the federal murder prosecution of former Stoughton police detective Matthew Farwell in the 2021 death of Sandra Birchmore. Jury selection begins October 5 in Boston before Chief Judge Denise J. Casper. The pretrial conference is September 17 and final witness lists are due September 21. This page will be updated at each stage.
The case in one paragraph
Sandra Birchmore was 23 and eight to ten weeks pregnant when she died in her Canton apartment in early February 2021. The state medical examiner ruled it a suicide. Three and a half years later, in August 2024, federal prosecutors charged Farwell with strangling her and staging the scene, alleging he had groomed her from the age of 15 through the Stoughton Police Explorers program, had sex with her while she was a minor and while he was on duty, and killed her to stop her from reporting it. He has pleaded not guilty. The defense says she died by her own hand.
Why it is a federal case
Murder is ordinarily a state crime. This one is in federal court because of the theory: that Farwell killed Birchmore to prevent her from communicating with law enforcement about a federal offense, which is the crime of killing a witness under the federal witness-tampering statute. That theory is also why the grooming allegations are not background but an element. The government has to prove not only that Farwell killed her but why.
On October 28, 2025, a superseding indictment added a second count for the death of her unborn child. On December 9, 2025, the government filed notice that “the Attorney General of the United States has directed the government not to seek the death penalty in this case.” The maximum on conviction is life.
The people
- Sandra Birchmore, 23 at her death, a former Stoughton Police Explorer.
- Matthew Farwell, former Stoughton detective, 27 when the indictment says he first had sex with Birchmore at 15. Held without bail since his arrest; the judge cited “very strong, if not overwhelming” evidence.
- William Farwell, his twin brother and a former Stoughton officer, one of three officers a Stoughton internal investigation found had inappropriate relationships with Birchmore. He is not charged. Reports this week indicate he may be called as a witness.
- Chief Judge Denise J. Casper, United States District Court for the District of Massachusetts.
Timeline
- 2010 to 2016. Birchmore participates in the Stoughton Police Explorers Academy, where Farwell volunteers. The indictment alleges sexual contact beginning when she was 15.
- December 2020. She tells Farwell she is pregnant.
- January 20, 2021. A friend calls Stoughton police to report the relationship.
- February 1, 2021. Birchmore dies in her Canton apartment. The medical examiner rules suicide.
- 2022. A Stoughton internal investigation finds three officers, including both Farwell brothers, had inappropriate relationships with her. All leave the department. No charges.
- August 2024. Federal grand jury indicts Matthew Farwell for killing a witness. He is arrested and held.
- October 28, 2025. Superseding indictment adds the unborn-child count.
- December 9, 2025. Government declines to seek the death penalty.
- January 23, 2026. Casper denies the defense motion to move the trial to Rhode Island: “Farwell has not met the high burden of demonstrating that pretrial publicity would prevent him from receiving a fair trial in this District.”
- March 9, 2026. Motion to dismiss the indictment denied.
- August 5, 2026. Prosecutors file a witness list of about 50, including roughly a dozen experts.
- September 1, 2026. Pretrial evidentiary hearing. Casper rules the defense may introduce Birchmore’s mental health history and suicidal ideation, and that prosecutors may call her a “victim.” Rulings on her journal entries, texts and the government’s expert witnesses taken under advisement.
- September 17. Pretrial conference.
- September 11 and 12. Government (68 names) and defense (97 names) witness lists filed, docket entries 259 and 260.
- September 21. Deadline for final witness lists.
- October 5. Jury selection. The trial is expected to run about twenty days.
The evidence fight
The trial will turn on two questions of proof, and the September 1 hearing showed where each side is weakest.
Homicide or suicide. The government’s medical case rests on Dr. William Smock, a strangulation expert who concluded homicide from a clasp-shaped imprint on her neck and a fractured neck bone, and on Dr. Michael Baden. The defense has challenged the reliability of both, arguing the findings are consistent with hanging. Casper has not yet ruled on the challenges. If she excludes or limits Smock, the government’s case is the circumstantial one: Farwell’s presence at the apartment, the phone and door evidence, and motive. If she admits him, the trial is a battle of forensic pathologists.
Motive and grooming. Dr. Lisa Rocchio, a forensic psychologist, would testify about grooming. Casper indicated she would allow “at least some” of that testimony, saying the disputes seemed “more suitable for cross-examination, as opposed to exclusion.” The defense theory, set out in its filings, is that the relationship was consensual by the time of her death and that Birchmore, with a documented history of suicidal thoughts, killed herself. Casper has allowed that history in. The government will answer that a pregnant woman who had just told the father, and whose friend had just reported him, had every reason to live and that the man she named had every reason to silence her.
The journals. Birchmore kept handwritten journals. Whether they come in, and under which hearsay exception, is the ruling still pending that could matter most. They are her own account of the relationship in her own words.
Update, September 12: the witness lists are in
Both sides filed their witness lists ahead of the September 21 deadline. The government’s list, docket entry 259, was filed September 11; Farwell’s, entry 260, was filed September 12. Independent court reporter Grant Smith Ellis posted images of both filings and a comparison: 31 names appear on both lists, 37 on the government’s only, and 66 on the defense’s only, for 68 government witnesses and 97 defense witnesses in all. The filings list names without roles.
Among the names on the government’s list are its experts Dr. William Smock, Dr. Michael Baden and Dr. Lisa Rocchio; Stoughton Police Chief Donna McNamara; State Police investigators John Fanning and Michael Lank; and William Farwell, the defendant’s twin brother, and his wife Angela. The defense list includes Dr. Mindy Hull, the state’s chief medical examiner, whose office ruled the death a suicide in 2021, and Kevin Albert, the former Canton police officer whose name figured in the Karen Read case. Ellis noted that Robert Devine, Farwell’s former supervisor at Stoughton, and Brian Tully, the State Police supervisor of the investigators, are not on the government’s list. A witness list is a disclosure, not a promise; either side may call fewer than it names.
What to watch
- September 17. Rulings on the experts and the journals may issue at or before the conference.
- September 21. The final witness lists. Whether William Farwell appears on either is the question being asked.
- October 5. Jury selection in a case Casper has already found can be tried fairly in Massachusetts despite coverage she acknowledged was extensive.
Who was Sandra Birchmore?
A 23-year-old Canton woman and former Stoughton Police Explorer who died in her apartment in February 2021 while eight to ten weeks pregnant. Her death was initially ruled a suicide.
What is Matthew Farwell charged with?
Killing a witness under federal law, and, since October 2025, a second count for the death of her unborn child. He has pleaded not guilty. The government is not seeking the death penalty.
Why is the case in federal court?
Because the charge is that he killed her to prevent her from reporting a federal crime to law enforcement, which is a federal offense regardless of where the killing occurred.
What is the defense?
That Birchmore died by suicide, that the scene was not staged, and that the government’s strangulation experts are unreliable. The judge has allowed evidence of her mental health history.
When does the trial start?
Jury selection begins October 5, 2026 in Boston before Chief Judge Denise Casper. The trial is expected to last about twenty days.
Is Farwell in custody?
Yes. He has been held without bail since his August 2024 arrest.
Facts from the indictment and superseding indictment as reported by CBS Boston, NBC Boston, The Boston Globe and WHDH, 2024 through September 2026, and from the docket in United States v. Farwell, No. 1:24-cr-10259 (D. Mass.). September 1 hearing rulings as reported by The Boston Globe and NBC Boston. Matthew Farwell is presumed innocent, and nothing alleged by the government has been proved. General information about federal and Massachusetts law, not legal advice.