Cop murdered pregnant mistress, tried to make it look like suicide to stop her from revealing he raped her when she was 15: Indictment

A federal grand jury on Wednesday indicted a now-former Massachusetts police officer for allegedly killing his 23-year-old pregnant mistress — a woman he had been having sex with since she was 15, authorities said.

Matthew Farwell, then an officer with the Stoughton Police Department, murdered Sandra Birchmore on Feb. 1, 2021, at her apartment in Canton, a suburb of Boston, said Josh Levy, acting U.S. Attorney for the District of Massachusetts. Levy told reporters Wednesday at a press conference that Farwell wanted to silence the pregnant Birchmore from revealing the statutory rape that occurred when she was 15.

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

The walls began closing in on Farwell, now 38, when Birchmore began telling friends he had been abusive and about their yearslong affair. Someone had also reportedly tipped off Stoughton police of Farwell’s transgressions when Birchmore was underage.

“When it became clear to Mr. Farwell that he could no longer control Sandra Birchmore, he allegedly silenced her permanently,” said Levy.

According to the indictment, Birchmore began attending the Stoughton Police Explorers, a program for young people interested in law enforcement, in 2010 when she was 12. Farwell became an instructor for the program when he was hired in 2012. A friendly relationship turned illicit by the time she was 15, prosecutors say. He allegedly would sneak off on duty to have sex with her.

The relationship continued into Birchmore’s adulthood.

“Building off the years of grooming, Farwell later cultivated a controlling and sometimes abusive relationship with Birchmore. He tracked her location with his cell phone and, as voluminous text messages demonstrate, he engaged in sexual violence,” prosecutors wrote in a memorandum in support of pretrial detention.

The violence included Farwell’s fantasies of sexual assault and interest in minors, feds say. In one text message from 2020, he allegedly described how he wanted to pin her down during sex and asked her: “Will you say Matt stop I’m 13 I’m not ready for this omfg please stop.”

Toward the end of 2020, feds say she told him she wanted to have a child together. The two “reached an agreement” that he would impregnate her “in exchange for her silence about his criminal conduct,” according to the indictment.

But when he got her pregnant in December 2020, he apparently wasn’t happy about it.

“He became physically violent with Birchmore. She told multiple friends that Farwell had pushed and shoved her, grabbed objects from her hands, and put her in a chokehold,” the indictment said.

Then, in January 2021, Farwell reportedly received word that a tipster had told an employee with Stoughton police about his illicit activities with Birchmore when she was a minor. He also learned Birchmore had told a friend about the statutory rape, the feds said.

Prosecutors allege that on Jan. 24, Farwell began to “take important steps” toward killing her, which included requesting and receiving a key to her apartment plus looking around the home for places to kill her.

“He inspected her bathroom and closet, places where items could be hung. His behavior was strange enough that Birchmore told multiple friends that she was concerned,” the memo said. “On February 1, 2021, Farwell decided to act. For him, that day provided at least two advantages: a blizzard was approaching greater Boston, ensuring that no one would notice Birchmore’s absence from work for several days; and Farwell’s wife was hours away from delivering their third child.”

Farwell allegedly texted Birchmore that he was on his way to her apartment and showed up wearing a face mask to conceal his identity. He then strangled her and “staged her apartment to make it appear Birchmore had committed suicide,” prosecutors said. He put her in a seated position and put a strap around her neck and doorknob, according to the feds. Canton Police officers found her body on Feb. 4 while conducting a welfare check after she didn’t show up for work.

A Massachusetts State Police investigation and autopsy initially determined she died by hanging and ruled the manner of death as suicide.

In subsequent days, he lied to MSP investigators and claimed he started having sex with Birchmore in 2020 when she was an adult, prosecutors said. He also allegedly claimed he hadn’t had sex with her in over a year, so it would seem he was not the father of the child.

The state hired a second medical examiner who found inconsistencies with the suicide conclusion and believed someone had strangled her, according to the indictment.

Feds also reportedly uncovered text messages and implicating Google searches he tried to delete.

Stoughton police began an internal investigation into Farwell following the murder and put him on leave. He resigned in April 2022. In a statement, Stoughton police Chief Donna McNamara called Birchmore’s death a “horrific injustice.”

“The allegations against the suspect, a former Stoughton Police Officer, represent the single worst act of not just professional misconduct but indeed human indecency that I have observed in a nearly three-decade career in law enforcement,” she said.

Feds arrested Farwell Wednesday on a charge of killing a witness or a victim. He faces life in prison if convicted.

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