A Massachusetts police detective has been charged in the strangulation death of a pregnant woman whose death was originally ruled a suicide.

Matthew Farwell, a former detective with Stoughton police in suburban Boston, was in court Wednesday following his arrest in the 2021 death of 23-year-old Sandra Birchmore. Farwell, 38, was arrested Tuesday and charged with killing a victim or witness. He's also accused of staging the crime scene to look like a suicide.

Officials say Farwell killed Birchmore in her apartment in the Boston suburb of Canton around Feb. 1, 2021, to prevent her from disclosing information about his long-standing sexual exploitation of her, saying the actions began when she just 15 years old.

Farwell's attorney, Sandra Gant, did not immediately respond to USA TODAY's requests for comment Wednesday.

"While Birchmore’s death was initially ruled a suicide, the federal investigation probed old evidence and revealed critical new evidence leading to the charge against Farwell," prosecutors said in a news release.

Here's what we know.

An alleged pattern of abuse ranged for almost a decade

Farwell was an officer for the Stoughton Police Department for about 10 years, and served as an instructor for the Stoughton Police Department’s Explorer’s Program, court documents say. The vocational educational program teaches children about careers in law enforcement.

Birchmore joined the program in 2010 when she was 12 years old. Farwell then allegedly used his authority to groom and sexually exploit her when she was 15 years old and kept having sex with her when she became an adult, federal prosecutors say.

Prosecutors also allege that Farwell engaged in sexual acts with Birchmore while on duty as a police officer, and concealed his activity by allegedly falsely representing his working hours. His sexual contact with Birchmore continued until her death in 2021, prosecutors say.

Birchmore was pregnant at the time of her death

Birchmore learned that she was pregnant in December 2020, and court documents say that she was excited about the prospect of being a mother and the pregnancy as a whole.

Soon after she told Farwell that he was the father of the child and expected him to be involved in their life, she told loved ones that he became violent with her, according to court documents.

Court documents also say that Farwell allegedly held Birchmore in a headlock and told her that he wished she were dead at one point during her pregnancy.

About two weeks before her death, Birchmore’s friend called the Stoughton Police Department, where Farwell worked, and referenced Farwell’s and Birchmore’s sexual relationship. He then is alleged to have sent Birchmore angry texts in response to the call, and a few days later asked her for a spare key to her apartment and not to tell anyone about it.

The court documents say that on Feb 1, 2021, Farwell murdered Birchmore to silence her.

"He strangled her to death when he knew she was several weeks pregnant," prosecutors said in court records. "He took steps to conceal the murder, including by repositioning Birchmore’s lifeless body and staging her apartment ... and lying to Massachusetts State Police detectives who were initially responsible for investigating Birchmore’s death."

If convicted, Farwell could face the death penalty or life in prison.

Fernando Cervantes Jr. is a trending news reporter for USA TODAY. Reach him at fernando.cervantes@gannett.com and follow him on X @fern_cerv_.

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