The “grisly” details on how a former Stoughton cop allegedly groomed, raped, impregnated and then killed a young woman he first met when she was 12 years old are darker than prosecutors could possibly describe in a press conference announcing his arrest.

Matthew Farwell, 38, of North Eastman, was a police officer for roughly 15 years — first for the department in Wellesley in 2008 and then for Stoughton four years later — before he resigned in April 2022 amid allegations that Stoughton Police Chief Donna McNamara described Thursday as “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.”

The allegations

“On February 1, 2021, Farwell killed … a young pregnant woman, whom he had spent years sexually exploiting,” Prosecutors wrote in a filing. “Farwell’s grisly crime was designed to conceal forever the truth about his years of criminal conduct.”

His alleged victim was Sandra Birchmore, who as a 12-year-old had an interest in possibly becoming a cop and signed up for the Police Explorers Academy, a youth program run by the SPD for which Farwell taught, in March 2010 to learn more and get some mentorship.

As law enforcement filings allege, it wouldn’t take long for the then-26-year-old Farwell to make his move on the young girl. By April 2013, he was regularly scheduling sex dates with the 15-year-old. As he would say in a text later, it was a “a big thing to get to be the first” and take her virginity as a full-grown man 12 years her senior.

Meeting

The Stoughton PD once had a photo of a beaming, preteen Birchmore standing between two officers and proudly wearing her black t-shirt with a badge decal and “Explorer” written under it.

Farwell started slow, sending the young girl — barely chest height to the officers seen in that photo — a Facebook friend request on Oct. 28, 2012.

Soon, witnesses and relatives would tell investigators, Farwell “cultivated a close relationship with Birchmore when she was a child.”

The 6-foot-4 Farwell, a sworn police officer and a supposed mentor, would take the high school freshman to study and “test prep” at the local library — where, later, he would text her he first developed sexual urges for her, investigators say.

Skipping prom for statutory rape

Birchmore would recall in a text to Farwell that she “had butterflies so bad the day you took my virginity” on April 10, 2013. “Best day of my life.” She could even recall “the specific class and seat that she was in when she realized that she was going to lose her virginity to Farwell,” an affidavit states.

“What would you have done if we never used a condom and I never pulled out…,” Farwell would text her as the pair “reminisced” about the first night he raped her.

Birchmore said she “wouldve (sic) still finished school” and that “I loved prom night! It was worth not going to prom.”

“How did you feel when I asked to make your dream come true?” Farwell wrote in a later conversation, adding that he wished he had started having sex with her a year earlier.

“Amazing!” Birchmore said.

An ultimatum

The feds don’t prosecute “murder,” which is a state-level crime, so instead Farwell is charged with killing a witness or victim. To back this up, they say Farwell killed Birchmore to silence her so she couldn’t reveal his alleged crimes of having statutory sex with her and doing so while on the clock for the Stoughton PD — which means wire fraud.

The investigation summarized in a filing by Special Agent Chenee Castruita of the Boston FBI points to at least 25 times the pair had sex while Farwell was still on the clock. It could happen at any time in the evening, and practically anywhere: at “Birchmore’s previous home in Stoughton, her more recent apartment in Canton, a Costco parking lot in Stoughton, and a Five Guys parking lot in Canton.”

During the course of the alleged illicit relationship, Farwell had gotten married and had children. On Oct. 5, 2020, an unidentified person told Birchmore that Farwell’s wife was pregnant with their third child. Eighteen of the 25 alleged encounters happened from that date on, but Birchmore had dreams of her future.

Electronic messages stemming from around that time “indicate that Birchmore presented Farwell with an ultimatum: that Farwell would have to try for having a baby with her and, in return, Birchmore wouldn’t disclose their relationship, which she knew had been illegal when she was underage and illegal while he was on duty.

Farwell agreed but tried to wiggle out of it anyway, investigators say, saying that he understood it to be to try once, not until it worked. Birchmore disagreed. On Dec. 28, 2020, it worked: she sent Farwell a text message with a hand-drawn poster celebrating the milestone: “Congrats we are going to be parents! 2021.”

“I literally have nothing to say right now how could you express that in text when I said I don’t appreciate it,” was Farwell’s immediate response, according to the feds.

Roughly a month later, on Feb. 1, 2021, prosecutors say, Farwell went to Birchmore’s apartment, strangled her to death and arranged the place to look like a suicide. She still had laundry in the wash and had just arranged for an infant photo shoot earlier that day.

Repercussions

While prosecutors were mum on who else, if anybody, could be charged in this “ongoing investigation,” or if Farwell himself could face additional charges, others see it as the start of a whole takedown of police corruption.

“She wanted to be a police officer. She admired them. She looked up to them, the people who she looked up to the most, or the ones who took advantage of her, they violated her and they ultimately killed her and her unborn child,” Allison Taggart, one of a handful of women standing outside the federal courthouse on Thursday for Farwell’s arraignment. “It was blatantly obvious what happened here, and they should not have gotten away with it for as long as they did.”

CAN END HERE

Taggart and the others came to the Birchmore case by way of the Karen Read case, at whose hearings they have been regulars.

“There’s some of the same police officers. It’s the same DA’s office. There’s a lot of the same players involved in both cases, covering up for each other. It’s sick,” she said.

Jennifer O’Donnell, another protester, said “This is the beginning of some really great things happening for both Sandra Birchmore and Karen Read, and I’m sure many, sadly, other victims throughout the Commonwealth over the years.”

Matthew Farwell (Stoughton Police Department via AP)

Protesters hold signs in front of the Federal Courthouse after the arrest of former Stoughton Police officer, Matthew Farwell charged in connection with the death of Sandra Birchmore. (Photo By Matt Stone/Boston Herald)

Estey holds signs in front of the Federal Courthouse after the arrest of former Stoughton Police officer, Matthew Farwell charged in connection with the death of Sandra Birchmore. (Photo By Matt Stone/Boston Herald)