A federal grand jury in Massachusetts indicted former Stoughton police officer Matthew Farwell on a new charge in connection to the death of Sandra Birchmore, a 23-year-old pregnant woman who prosecutors say he strangled to death in 2021.

Birchmore was found dead inside her Canton apartment. Her death was initially ruled a suicide, but Farwell was later charged with strangling her.

Farwell was previously only charged with killing a witness or victim. On Tuesday in a superseding indictment, a second count under the state's protection of unborn children law was added.

Prosecutors allege that Farwell engaged in sexual activity with Birchmore before she was 16 years old, at times when he was on duty as a Stoughton police officer. The alleged sex acts took place over the course of several years, prosecutors said.

According to the indictment, around December 2020, Birchmore learned that she was pregnant and told Farwell that he was the father. On January 20, 2021, a friend of Birchmore's called the Stoughton Police Department and told an employee that Farwell had been having sex with Birchmore.

Birchmore died on February 1, 2021, and prosecutors said Farwell staged the scene to make it look like she had died by suicide.

The superseding indictment revealed for the first time that Birchmore was between 8 and 10 weeks pregnant with a baby boy.

The new charge says that by allegedly killing Birchmore, Farwell "thereby caused the death of a child in utero at the time the conduct took place."

Farwell is scheduled to face trial on October 5, 2026. Federal prosecutors must decide by January 20, 2026 if they will seek the death penalty.