STOUGHTON, MA – A former Massachusetts police detective faces federal murder charges after prosecutors say he strangled a pregnant 23-year-old woman and staged her death to look like suicide when she revealed she was carrying his child.
Matthew Farwell, 39, was indicted in federal court last month for allegedly killing Sandra Birchmore in February 2021. The former Stoughton Police Department detective pleaded not guilty to charges of killing a witness or victim. Federal authorities claim Farwell began grooming Birchmore when she was just 15 years old and he was 27, using his position as an instructor in the department’s youth explorer program to gain her trust.
The young teacher’s assistant was found dead in her apartment bedroom on February 4, 2021, after missing work at a suburban Boston elementary school. A duffle bag strap was wrapped around her neck in what initially appeared to be a suicide. The state medical examiner’s office ruled it a self-inflicted death three months later, but Birchmore’s family never accepted that conclusion.
Federal prosecutors paint a much darker picture. They allege Farwell murdered Birchmore on February 1, just days after another person reported their inappropriate relationship to the police department. That complaint reached Farwell himself, who prosecutors say “angrily demanded” the department employee who received the tip never tell anyone about it.
The relationship between Farwell and Birchmore allegedly began when she participated in the police explorer program as a teenager. According to investigators, Farwell had sex with the young woman while on duty, exploiting his authority over someone who had admired law enforcement since childhood. Text messages and social media communications revealed disturbing patterns of manipulation and control that continued for years.
Birchmore wasn’t the only officer involved with the victim. William Farwell, Matthew’s twin brother and fellow police officer, admitted to sexual contact with Birchmore in 2020. Investigators also discovered Facebook messages between Birchmore and someone using the alias “Marty Riggs,” believed to be former deputy chief Robert Devine, who ran the explorer program. The messages discussed meeting for sex.
Police Chief Donna McNamara launched an internal investigation after learning about the relationships, ultimately examining tens of thousands of messages. Her 18-month probe revealed what she called a “sustained and deliberate combination of lies, deceit and treachery” by three of her officers. All three men resigned during the investigation.
“They dehumanized her. It’s vile,” McNamara said in her first media interview about the case. “I am sorry that she was treated so horrifically by three men from my department. She didn’t deserve that.”
The chief believes the January 20, 2021 complaint about Farwell’s relationship with Birchmore served as a catalyst for her death less than two weeks later. Farwell admitted to visiting Birchmore’s apartment on February 1 to end their relationship but claimed he left after an argument. Prosecutors allege he actually strangled her that day.
DNA testing later revealed that Matthew Farwell wasn’t actually the father of Birchmore’s unborn child, though prosecutors say he believed he was when she told him about the pregnancy. Investigators found evidence that Farwell had responded “poorly” to news of the pregnancy and had previously physically assaulted Birchmore.
The case took a dramatic turn after McNamara held a public news conference in September 2022 denouncing her officers’ behavior. Federal authorities reached out for information following her announcement, eventually bringing charges that state investigators had declined to pursue. For over a year, state police had told Birchmore’s family there wasn’t enough evidence to charge Farwell with murder.
McNamara recommended all three officers be permanently barred from law enforcement in Massachusetts. The Farwell brothers entered voluntary decertification agreements, while Devine is fighting to keep his certification. Birchmore’s estate has filed a lawsuit against the three former officers and the police department.
The medical examiner’s office continues to stand by its suicide ruling despite the federal murder charges. No trial date has been set for Matthew Farwell, who remains free after pleading not guilty to the federal charges.
