Sandra Birchmore, 23 and pregnant, was found dead in her Canton apartment on February 4, 2021, initially ruled a suicide. Former Stoughton officer Matthew Farwell was arrested on August 28, 2024 and charged with killing a witness and causing the death of an unborn child; he has pleaded not guilty. Surveillance puts him in her building from 9:14 to 9:43 p.m. on February 1, 2021, and his sperm was on the noose, but the DNA link came through YSTR testing that cannot separate identical twins. The death record was amended to asphyxia with the manner undetermined, and the officer who first ruled suicide admitted he did not collect the ligature. The defense argues investigators pressured the medical examiner to change…