Trooper Matthew Dunne said investigators found no sign of forced entry or a struggle in Birchmore’s Canton apartment. He testified that a camouflage duffel bag was missing a strap that appeared to be the ligature found around her neck. Investigators did not find a suicide note at the apartment, he said, though handwritten notes were later shown in court, including one listing ways to die and another giving reasons not to.

Dunne said he did not attend Birchmore’s autopsy because investigators had no information indicating foul play at the time. He also testified that two interviews with Farwell and one with Farwell’s brother were not recorded; he took no notes during the Feb. 11, 2021, interview with William Farwell. Dunne said investigators later concluded Matthew Farwell’s account of when his sexual relationship with Birchmore began was inaccurate, based on text messages and other investigative work.

Defense attorney Kimberly Stevens questioned Dunne about what investigators knew of Birchmore’s mental health and the handling of the case. She also asked about surveillance footage showing Farwell entering the apartment building. Dunne said Farwell appeared to have snow on him and wore heavy-soled boots, but he saw no salt or boot-tread marks in the bedroom.

State police crime lab analyst Alicia Zimmerman testified that tests of Birchmore’s blood found no alcohol, antifreeze, rubbing alcohol, nail polish remover or illicit drugs. The prescription antidepressant Zoloft was present. Zimmerman said she did not know which medications Birchmore was taking or whether the Zoloft level was therapeutic.

Robert Kuhn, a former Stoughton High School resource officer, said he met Birchmore when she was 11 or 12 through the Stoughton Police Explorers, a youth program in which Farwell also participated. Kuhn described Birchmore as a squad leader who looked up to police and military members. He said he never knew her to be suicidal and had not encountered a seated or partial suicide in his 20 years as an officer.

Farwell is accused of strangling Birchmore in early 2021 and staging her death as a suicide. Prosecutors allege he began sexually exploiting her when she was 15, while he was involved with the Explorers program, and continued the relationship after she became an adult. They say he killed her after she told him she was pregnant and that he was the father; DNA testing later showed he was not the father of the unborn child. These are allegations, and Farwell is presumed innocent unless proven guilty.

The trial is expected to last about five weeks. Kuhn is scheduled to return Thursday, with Birchmore’s friend Leslie Davis, Stoughton Police Chief Donna McNamara and state police Trooper Nicholas Guarino also expected to testify.