Farwell trial: Medical examiner testifies; twin brother takes stand

The medical examiner whose 2021 suicide ruling stood in the way of charges for years took the stand Monday in the federal murder trial of former Stoughton police detective Matthew Farwell, as both sides fought over how Sandra Birchmore died.

Monday in court

Diala Alkhalil, a licensed mental health counselor who treated Birchmore as a child and again in the five years before her death, returned to the witness stand Monday at the John Joseph Moakley U.S. Courthouse in Boston, the Globe reported.

On Friday, under questioning by prosecutors, Alkhalil told jurors that she had seen Birchmore the day before she died and saw no sign that she was at risk. She described her as resilient and said she was excited about her pregnancy, Boston.com and the Globe reported.

On Monday, defense attorney Joanne Daley took her through Birchmore's mental-health history, including grief after the deaths of her mother and grandmother, and a 2017 diary entry the jury had already seen, according to the Globe. Daley also pointed to a difference between Alkhalil's trial testimony and what she told a grand jury about something Birchmore had told her. Alkhalil acknowledged the earlier answer and said she had been more distressed at the time, the Globe reported.

Next came Dr. María Del Mar Capó-Martínez, the forensic pathologist at the state Office of the Chief Medical Examiner who performed Birchmore's autopsy in February 2021. She testified for several hours as a prosecution witness, the Globe reported.

Under questioning by prosecutor Elizabeth Riley, she said her office depends on police and other agencies for information, and that without all of it a manner of death may not be determined accurately, according to the Globe. She told jurors she had not been given information about Birchmore's phone or its messages, witness statements, or DNA testing before she finalized her report, and that she was not asked to consider whether the death was a homicide or suspicious, the Globe and Boston.com reported. Shortly before her May 2021 report, a State Police investigator told her office by email that there was nothing new to report, she testified. She said changing a manner of death is unusual and that she recalls doing it only once or twice.

Under cross-examination by defense attorney Kimberly Stevens, Capó-Martínez said she did not feel pressured to change her finding, including after a meeting between state and federal authorities about the case, the Globe reported. The defense also had her review how her office handled Birchmore's belongings in 2021; she said they would have been handled differently had there been any sign of foul play, according to Boston.com.

Late in the day, Farwell's twin brother, William Farwell, also a former Stoughton police officer, testified under a grant of federal immunity, the Globe and Boston.com reported. He told jurors he had a relationship with Birchmore beginning in 2018, when she was an adult, and that he did not know about his brother's relationship with her. He is not charged in the case. Both brothers resigned from the Stoughton department in 2022 after an internal-affairs review, the Globe reported. His testimony resumes Tuesday.

Why the medical examiner matters

Capó-Martínez ruled Birchmore's death a suicide in May 2021, the Globe reported, and the Globe has called that ruling one of the biggest hurdles for the prosecution. That finding was part of the reason Norfolk District Attorney Michael Morrissey's office did not bring charges.

In April 2026, she withdrew the suicide finding and listed the manner of death as undetermined, according to the Globe and Boston.com.

Prosecutors say her first ruling was premature and was made without key evidence, including the defendant's messages with Birchmore and building surveillance video showing Farwell coming and going on Feb. 1, 2021, the last day anyone heard from her, the Globe reported. The defense has suggested that federal prosecutors pressured her to change her finding.

Both sides plan to call more medical experts. Prosecutors are expected to call another medical expert on Tuesday, the Globe reported; they have listed Dr. William Smock, a forensic physician the FBI consulted, who concluded that Birchmore was killed. The defense plans to call Dr. Thomas Andrew, a former New Hampshire chief medical examiner who, according to court papers, could not determine the manner of death and could not rule out suicide, the Globe reported.

What prosecutors allege

Prosecutors allege that Farwell began sexually abusing Birchmore when she was a minor in the Stoughton Police Explorers program, where he was an instructor, and that the relationship continued for years, according to the U.S. Attorney's Office and court reporting.

They say that in early 2021 Birchmore was pregnant and that both she and Farwell believed he was the father. Prosecutors allege Farwell killed her in her Canton apartment on Feb. 1, 2021, and staged the scene to look like a suicide, so that she could not tell his wife or authorities about his alleged crimes. DNA testing later showed that Farwell was not the father, Boston.com and the Globe reported.

A federal grand jury's superseding indictment charges him with killing a witness or victim to prevent communication with law enforcement, and with causing the death of an unborn child, according to the U.S. Attorney's Office. The office has said that the second charge carries a mandatory life sentence on conviction.

What the defense says

Farwell's lawyers, Kimberly Stevens and Joanne Daley, say he went to Birchmore's apartment to end the relationship and told her he was not the father, and that she died by suicide afterward. They have pointed to her mental-health history and say her final days were marked by financial stress and worry about her pregnancy, the Globe and CNN reported. They argue the government cannot prove beyond a reasonable doubt that he killed her.

Farwell, who was arrested in August 2024 and has been held since, has pleaded not guilty.

What's next

William Farwell returns to the stand Tuesday morning, and the Globe reported that he is expected to be the government's second-to-last witness and that the defense is likely to begin its case Wednesday. The trial opened with statements on Oct. 9 before U.S. District Judge Denise J. Casper.

NewsCubby will keep following the case.

*If you or someone you know is struggling or in crisis, call or text 988, the Suicide & Crisis Lifeline, or chat at 988lifeline.org. For mental health or substance use treatment referrals, SAMHSA's National Helpline is free, confidential and open 24/7 at 1-800-662-4357. If you or someone you know has been affected by sexual abuse, RAINN's National Sexual Assault Hotline offers free, confidential support 24/7 at 800-656-4673 or rainn.org. In an emergency, call 911.*

*Credits: court reporting from the Boston Globe, Boston.com and CNN, plus U.S. Attorney's Office case records. NewsCubby was not in the courtroom; this report summarizes that coverage in our own words. Photo: 4300streetcar / Wikimedia Commons, CC BY 4.0 (cropped). NewsCubby articles are produced with AI assistance and reviewed by humans.*

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