Here is a strange way to run a murder trial: before the prosecution can argue that the defendant did it, it first has to argue that the state police who originally said nobody did it were wrong, and wrong for comprehensible reasons. In the federal trial of Matthew Farwell, the former Stoughton detective charged with killing Sandra Birchmore in 2021 and staging her death as a suicide, the government is in the awkward position of putting the state’s own earlier investigation on trial alongside its case, the Boston Globe reports. We covered the competing accounts of Birchmore’s last night when the trial opened; by now a third account has taken centre stage, which is the account of who investigated what, and when, and why they stopped.
The mechanics of the problem are worth setting out. Birchmore was found dead in her Canton apartment on Feb. 4, 2021. The Norfolk district attorney’s office under Michael Morrissey, relying on the state medical examiner at the time, concluded she died by suicide. The state medical examiner now says the manner of death is undetermined, which is the sort of quiet revision that tends to arrive with an indictment attached: federal prosecutors charged Farwell in August 2024 with killing her. He has pleaded not guilty. His defense is that Birchmore killed herself after Farwell, married and 40 now, broke up with her and denied paternity of the child she was carrying. DNA testing later excluded him as the father.
So the prosecution has to prove, beyond a reasonable doubt, a homicide that a prior state investigation said never happened. “It is unusual that the prosecution, state and federal, would be at odds,” Glenn MacKinlay, a former homicide prosecutor now at McCarter & English, told the Globe. But, he added, once the feds “determined that there was a homicide committed here,” discrediting the state investigation wasn’t really optional. It was the load-bearing wall of the case.
And this is where the incentives come in, because they always do. Victor Hansen of New England Law Boston framed the prosecution’s theory of the state probe plainly: the point is to show a motive for the initial investigation to fail. “They were giving this guy a break. They didn’t want to go after one of their own,” as Hansen described the argument. Investigators investigate; when the subject of an investigation is a fellow police officer, and the investigating agency has recently had other embarrassments, the question of how hard they looked becomes a question a jury can actually be asked to answer. Prosecutors are, per Hansen, trying to get ahead of the defense using the state’s suicide conclusion as a line of attack.
What did the state investigation actually do? According to trial testimony described by the Globe, State Police closed the case without seeking any search warrants and without attending Birchmore’s autopsy. They interviewed Farwell and his twin brother, William, separately — in parking lots, without recordings or notes. “That’s too important an interview to be conducted on the fly like that,” one expert told the paper. Trooper Matthew Dunne, an investigator from Morrissey’s office, testified at the prosecution’s prompting about steps he did not take: he didn’t interview Birchmore’s neighbors, and he didn’t notice that her flamingo pendant necklace had snapped along the chain — a detail the prosecution offers as a sign of struggle, and which her family later found where her body had been discovered.
The cost of not seeking warrants is not abstract. Prosecutors say it meant never searching Farwell’s residence or vehicle in the days after the body was found, and never asking for the clothing he was seen wearing on surveillance video when he visited Birchmore’s apartment on Feb. 1, 2021, three days before her body was discovered. Farwell deleted his Facebook account and told investigators he had deleted every message he exchanged with Birchmore after leaving her apartment that night. Evidence has a shelf life, and an investigation that never opens the refrigerator gets to be surprised by what’s gone.
Then there is what the FBI found when it took the case on a referral from a civilian and two police officers, including Brian Holmes, the former Stoughton deputy chief who ran an internal review of the department’s contact with Birchmore. As we’ve reported earlier in this trial, the relationship between Farwell and Birchmore stretches back to when she was a 15-year-old in the Stoughton Police Explorers program. Special Agent Heidi Kelsch testified that the federal probe began with whether Farwell had used his badge to deprive Birchmore of her constitutional rights by abusing her from that age, then widened to her death. Agents subpoenaed police reports, medical and school records, and got warrants for her Facebook, Google and iCloud data, plus Farwell’s iCloud and Google searches. They turned up roughly 40,000 messages between Birchmore and Farwell — many, prosecutors wrote in court papers, never examined by State Police. “I went line by line through hundreds of thousands of messages,” Kelsch testified.
The corroboration piece is the sort of thing that makes prosecutors quietly happy and defense lawyers quietly tired. Birchmore’s medical records showed she mentioned being tutored by a police officer in March 2013 and asked about birth control in May 2013 — consistent with texts about Farwell tutoring her at the library, and with messages about her missing school to meet him and about conceiving a child. The feds interviewed about 130 witnesses. Trooper Dunne, for his part, conceded that Farwell told state investigators he had started having sex with Birchmore in 2020, only two or three times, and that “interviews and cellphone data” showed the contact began much earlier. A witness lying to investigators about the timeline of a relationship is not proof of murder, but prosecutors tend to ask juries: why lie about that, if everything else is innocent?
The defense’s counter-move is jurisdictional rather than factual. Attorney Joanne M. Daley argued early in the trial that prosecutors want to distance themselves from the state investigators while still using some of the evidence those same investigators gathered — and that the state and the FBI are all simply the government, the same government now prosecuting Farwell. It is a fair point, and also a preview: expect closing arguments to feature the state’s suicide conclusion as the reasonable-doubt engine, which is exactly the attack Hansen said prosecutors are prebutting.
Context matters here, and it is not flattering. Troopers from Morrissey’s unit were also accused of bungling the investigation into the death of Boston police Officer John O’Keefe; last year a jury acquitted Karen Read of his murder after she attacked the credibility of the same investigative apparatus. Once a jury in one county has been persuaded that an agency’s work can’t be trusted, the next jury starts the movie already knowing the spoiler. State Police and Morrissey’s office declined to comment, citing the ongoing trial.
Alan Tuerkheimer, a jury consultant in Chicago, told the Globe that the whole thing comes down to perceived cleanliness: if the federal prosecution “comes off as sound and fair, and not trying to back into a result,” jurors will follow it, but doubts about its motives can become doubts about guilt beyond a reasonable doubt. That is probably right. The government is asking twelve people to believe that one set of public servants looked away and that another set, arriving three years later, saw clearly. Both halves of that story are about institutions, which is a heavy lift in a courtroom — and, lately in Norfolk County, maybe not such a heavy one.