Jury selection begins Tuesday in the trial of Sandra Birchmore’s alleged killer. Here’s a quick primer on the case.

The trial of former Stoughton police detective Matthew Farwell is scheduled to begin this week, with jury selection set to commence Tuesday in federal court in Boston. Farwell allegedly killed Sandra Birchmore while she was pregnant and staged the scene to appear as if it were a suicide.

The high-profile trial comes more than five years after Birchmore was found dead in her Canton apartment. A state investigation initially ruled her 2021 death a suicide, but an FBI investigation later led to Farwell’s indictment. 

Below, find a quick guide to the case. 

Prosecutors say Farwell, 40, groomed Birchmore from the time she was a participant in the Stoughton Police Explorers Academy. Farwell was an instructor in the program. Farwell allegedly committed statutory rape against Birchmore in 2013, when he was 27 and she was 15. Farwell allegedly maintained a sexual relationship with her for years, which sometimes included meetings while he was on the clock working for the town of Stoughton. 

Birchmore asked Farwell, who was married with multiple children of his own, to have a child with her, prosecutors say. She became pregnant in late 2020 and told Farwell that they were going to be parents. Angry at Birchmore and afraid that she would expose his yearslong abuse of her, Farwell murdered her in February 2021, prosecutors allege. 

Farwell’s defense attorneys say that Birchmore was upset that Farwell was ending their relationship and died by suicide. 

DNA testing has since excluded Farwell as the father of the fetus, The Boston Globe reported. 

Farwell faces two federal charges: killing a witness or victim and killing a child in utero.

Prosecutors have to prove beyond a reasonable doubt that Farwell killed Birchmore in order to prevent her from telling authorities about the “commission or possible commission” of federal offenses including the deprivation of her rights, coercion, and wire fraud. 

Prosecutors must show that there was a reasonable likelihood that a communication from Birchmore would have been made to a federal law enforcement agency, but they do not have to prove that Farwell or Birchmore necessarily had federal law enforcement in mind. 

Regarding the second charge, prosecutors must simply prove that Farwell killed Birchmore and caused the death of her unborn child.

The key evidence is expected to include thousands of text messages between Farwell and Birchmore. Many of these messages have been included in court documents, and they allegedly show how the dynamic between Farwell and Birchmore changed in the last few months of her life.

Much of the trial is also expected to center on Birchmore’s injuries. Prosecutors have pointed to medical experts that say her injuries are more commonly found in strangulation victims than those who have killed themselves. The defense is also planning to call medical experts who could offer different conclusions. 

Jury selection should last at least a few days, with opening statements not expected before Friday at the earliest, the Globe has reported. More than 100 possible witnesses could take the stand. Court proceedings will generally run from 9 a.m. to 4 p.m., but the judge overseeing the trial has left open the possibility of scheduling some half-days that conclude at 1 p.m.