Dateline: The Betrayal of Sanda Birchmore - Everything we know about the latest true crime episode 

NBC Dateline presented an explosive new episode, The Betrayal of Sandra Birchmore, on September 19, 2025, at 10 p.m. ET/PT.

The episode delves into the grim circumstances of Sandra Birchmore’s death, a young Massachusetts woman whose investigation rocked a regional police force and garnered nationwide media attention. The episode has been featured in headlines for its never-before-seen interviews of Birchmore’s relatives, a victim’s rights representative, and law enforcers, alongside new, revealing information.

Sandra Birchmore was a 23-year-old teacher’s aide who was found dead in her apartment in February of 2021, just after announcing to her family members that she was pregnant. While her death was first termed a suicide, new evidence brought back the case as a homicide investigation.

During the investigation, allegations popped up against a few members of the Stoughton Police Department, including the man who was charged with abusing Birchmore for years before reportedly taking her life.

The Betrayal of Sandra Birchmore offers an in-depth look at the tragic betrayal, the investigation that followed, and the forensic evidence that helped uncover the truth.

Dateline: The Betrayal of Sandra Birchmore

Dateline’s newest episode looks at one of Massachusetts’ most horrific recent cases: the death of Sandra Birchmore, who was discovered dead in her Canton apartment on February 4, 2021.

Sandra was a vibrant young teacher’s aide who had announced to her family that she was pregnant days before her death. On the morning of her death, she was reportedly up and moving around, showing no indication of the hopelessness typically associated with suicide.

Although state authorities at first labeled her death a suicide, Sandra's family did not accept it. They protested with the help of privately hired forensic experts and criminal proceedings against the officers who abused her, believing Sandra was murdered and was a victim of a crime.

A major twist occurred in summer 2024, after federal prosecutors indicted ex-Stoughton detective Matthew Farwell in the killing of a witness or victim. Prosecutors describe how Farwell, 39, met Sandra when she was a teenager during a police youth program.

Over years of grooming and abusing her, he strangled her when he discovered he may have gotten her pregnant. He then set up the scene to make it look like a suicide, an act initially unchallenged, but later fell apart under pressure from Sandra's relatives and new forensic evidence.

Stoughton Police Chief Donna McNamara apologized for the horrific treatment Sandra received by members of the department, condemning the department's members for the way in which Sandra was "dehumanized."

McNamara told Dateline:

“I am sorry that she was treated so horrifically by three men from my department. She didn’t deserve that. They dehumanized her. It’s vile.”

There were also allegations against Matthew’s twin brother, William Farwell, and a former deputy chief, both of whom were accused of improper relationships with Sandra. DNA tests would later confirm Matthew Farwell was not the father of Sandra’s unborn child, putting yet another twist into the case.

Sandra Birchmore's murder exposed grave issues at the Stoughton Police Department and raised bigger questions about the culture of police-operated youth programs. The Dateline segment explores investigative failures, abuse of authority, misconduct, and years of betrayal.

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Correspondent Andrea Canning anchors the story, drawing Sandra Birchmore's investigation into larger-scale Massachusetts cases, the Karen Read murder among them.

The Dateline episode features exclusive interviews with Chief Donna McNamara, members of Birchmore's family, their pastor, and lawyers, giving important context and personal meaning to the story.

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