Massachusetts cop Matthew Farwell charged with strangling murder of pregnant woman Sandra Birchmore

A Massachusetts police detective has been charged with strangling a pregnant woman and framing her death as suicide in a bid to prevent her from revealing the extent of their relationship.

Matthew Farwell, 38, is accused of killing 23-year-old Sandra Birchmore in February 2021, within weeks of her telling him she was pregnant with his child. 

Police allege Farwell embarked on a sexual relationship with Birchmore when she was just 15. He would have been 26 at the time.

The federal indictment, seen by DailyMail.com, accuses Farwell of beginning that relationship when he was an instructor for the Stoughton Police Department’s Explorer’s Program, which was dedicated to teaching young people about careers within law enforcement.

Birchmore joined the program in 2010, when she was 12. Throughout her time in the program, Farwell was her instructor.

Police allege Farwell, who is married with children, was motivated to kill her in order to prevent her from speaking out about the relationship, exposing not only a years-long extramarital affair, but alleged criminal conduct too.

A Massachusetts police detective has been charged for the strangling death of pregnant woman Sandra Birchmore (pictured)

Acting U.S. Attorney Joshua Levy on Wednesday said: 'Sandra Birchmore survived years of grooming, statutory rape and then sexual violence, all at the hands of Matthew Farwell, who was employed throughout the relationship as an officer and then detective for the Stoughton Police Department.'

The former cop was arrested by an FBI SWAT team on Wednesday morning and federally indicted a short time later.

The 23-year-old Birchmore was three months pregnant when she was found dead inside her home in 2021.

Her death was initially believed to be a suicide, but a pathologist who was hired by her family disagreed with that assessment and argued that she had been murdered. 

Police now allege Farwell 'staged her body and apartment to make it appear as if Birchmore committed suicide.'

Police allege Farwell had a sexual relationship with Birchmore since she was 15 years old

'Farwell allegedly used his authority and access to groom, sexually exploit and ultimately sexually abuse Birchmore when she was 15 years old and continued to have sex with her when she became an adult,' the US Attorney's Office said in a statement.

In the statement, Farwell is accused of engaging in 'sex acts with Birchmore while on duty as a Stoughton police officer.'

Police have since revealed he also has a 'spouse and children' who he lives with in North Easton, Massachusetts.

'To conceal this activity, it is alleged that Farwell falsely represented that he had worked certain hours, when in fact he was not working but engaging in sex acts with the then-minor victim.

Police claim Birchmore had told loved ones prior to her death that Farwell 'became violent' when she revealed she was pregnant with his child 

'Farwell’s sexual contact with Birchmore continued until her death on Feb. 1, 2021,' the statement reads. 

Farwell served as a police officer for more than a decade. The alleged crime took place when he was still working for Stoughton Police Department. 

Police claim Birchmore had told loved ones prior to her death that Farwell 'became violent' when she revealed she was pregnant with his child.

The police statement said: 'At one point while she was pregnant, Farwell allegedly held Birchmore in a headlock and told her that he wished she were dead.'

Police claim Birchmore's friend called the Stoughton Police Department on January 20 and disclosed the sexual relationship between the 23-year-old and Farwell.

The former cop was arrested by an FBI SWAT team on Wednesday morning and federally indicted a short time later

Farwell was allegedly outraged and sent furious text messages to Birchmore and, several days later, asked her to provide him a key to her apartment - and to keep it a secret.

Police allege Birchmore became increasingly uncomfortable with Farwell's actions, making Farwell increasingly suspicious that she planned to disclose the nature of their relationship. 

In a motion urging the state to keep Farwell in pre-trial detention, investigators on the case said: 'There are no conditions of release that will protect the community from a defendant whose conduct reveals such an indifference to human life.

'Farwell faces a mandatory life sentence for killing Birchmore. The weight of the evidence is overwhelming.'