What federal charges were brought against Matthew Farwell in connection to Sandra Burchmore's death?

Matthew Farwell, a former Massachusetts police officer, was indicted by a grand jury last year on federal charges related to the murder of his pregnant girlfriend, Sandra Burchmore. Specifically, he was charged with killing a witness or victim. According to the indictment, Farwell is accused of killing Sandra Burchmore "with malice aforethought, willfully, deliberately, maliciously and with premeditation." Federal investigators have determined that Sandra was murdered, and they believe Farwell was responsible for her death, pointing to a premeditated act rather than an accidental death.