Closing arguments began Friday in the trial of a former Massachusetts police officer accused of killing a pregnant woman to keep her from revealing he had begun sexually abusing her when she was 15.

Federal prosecutors say Matthew Farwell killed Sandra Birchmore, 23, and tried to stage her death as a suicide in 2021 after learning she was pregnant with what he thought was his child.

At the time, Farwell was a married detective with the Stoughton Police Department, where Birchmore had participated in a youth program as a child.