Twin Brother Returns to Stand as Farwell Faces Life Sentence

William Farwell will return to the federal witness stand Tuesday morning in South Boston.

The former Stoughton police officer is testifying in the trial against his twin brother, Matthew Farwell, who is accused of killing 23-year-old Sandra Birchmore and her unborn child.

Prosecutors argue Matthew Farwell staged Birchmore's death in February 2021 to hide a long-term affair that began when she was 15.

The defendant faces charges for killing a witness and causing the death of an unborn child, with a plea of not guilty to both counts.

William Farwell spoke for roughly 30 minutes late Monday afternoon. He admitted to a sexual relationship with Birchmore but is protected from prosecution by a federal immunity deal.

The immunity agreement shields him from a charge of having sex while on duty. He told the jury their relationship started when Birchmore was 20 and that he was unaware of her relationship with his brother at the time.

Matthew Farwell's defense attorney conceded the couple had an affair but argued he did not believe the child was his.

The defense claims Birchmore killed herself after the breakup. DNA evidence later identified the father as a U.S. Army recruiter who also testified under immunity.

A guilty verdict for Matthew Farwell carries a mandatory life sentence.