Ex-detective accused of strangling pregnant woman he abused as teen and trying to make death look like suicide

A former police detective in Massachusetts accused of strangling a woman who had recently told him she was pregnant with his child and then staging her death to appear as a suicide has been charged in her 2021 death, federal prosecutors said Wednesday.

They allege that Matthew Farwell killed Sandra Birchmore years after he began grooming her as a youth in the Stoughton Police Explorers Academy. Farwell was an instructor in the program designed to foster an interest in police work and worked for the Stoughton Police Department from 2012 to 2022.

Sandra Birchmore sought direction in law enforcement. via Facebook

Farwell, 38, began having sex, including while on duty, with Birchmore when she was 15, Acting U.S. Attorney Joshua Levy said at a news conference Wednesday.

She “survived years of grooming, statutory rape and then sexual violence, all at the hands of Matthew Farwell," Levy said.

Farwell befriended her, contacted her online and went to the library with her before he began committing statutory rape, Levy said.

Birchmore's alleged sexual abuse as a part of the police Explorers club was included in a Marshall Project investigation, published in partnership with NBC News in May, about abuse allegations in law enforcement Explorer posts across the country. The program, created by the Boy Scouts of America, aims to teach teens and young adults about policing. 

Prosecutors said Farwell killed Birchmore, 23, on Feb. 1, 2021, in her Canton, Massachusetts, apartment when he could no longer control her and as word began to get out that he had been having sex with her for years.

“He allegedly silenced her permanently,” Levy said.

Birchmore's death was initially ruled a suicide by authorities.

Farwell has been charged with one count of killing a witness or victim. He was arrested by the FBI in Revere, Massachusetts, on Wednesday.

A lawyer for Farwell did not immediately respond to a request for comment.

The news of his arrest comes two years after the chief of the Stoughton Police Department announced that Farwell and two other former officers, including Farwell's twin brother, at the agency had inappropriate relationships with Birchmore.

The brother has previously denied the allegations.

That conclusion came from a lengthy internal affairs investigation prompted by Birchmore's death, said the chief, Donna McNamara, who called the former officers' behavior "deeply disturbing."

“Through a sustained and deliberate combination of lies, deceit and treachery, they violated the policies and the core values of the Stoughton Police Department,” McNamara said at the time. "Not to mention human decency.”

The department recommended that their certifications as police officers be permanently revoked so they cannot serve in law enforcement anywhere in the country, McNamara said.

In a statement Wednesday, McNamara said it had been her priority for the last three years to ensure justice in the case.

"Sandra Birchmore received no justice during her life," she said. "It is imperative that justice be served in her death, and today’s actions appear to bring our society one step closer to justice.”

This is a developing story. Please check back for updates.