Testimony began Tuesday in the trial of Matthew Farwell, the former Stoughton, Massachusetts police officer accused of killing Sandra Birchmore and her unborn baby.
Federal prosecutors said Farwell met Birchmore when she was 13 years old and a member of the police department's youth program. Investigators said he groomed Birchmore for years and began having sex with her when she was 15 and he was 27.
Birchmore was found dead at the age of 23 in her apartment in Canton in February 2021. Her death was initially ruled a suicide.
Jurors saw surveillance footage from the apartment building showing Birchmore in the final moments before she died and Farwell, hooded and masked, entering the building that same night.
The first prosecution witness was Heather Cheever, a Stoughton police detective. She said she's responded to several suicides but had never seen one where someone hanged themselves from the ground in a seated position.
Cheever said she had known Birchmore since she joined the Stoughton Police Department in 2013, when Birchmore was part of the police explorers program for kids. She said Birchmore was very respectful and looked up to every officer she met.
"She wanted to become a police officer herself," Cheever said.
The prosecutor asked Cheever if she knew that Farwell was tutoring Birchmore one-on-one at the library. Cheever said she did not, but said she would've asked questions if she did know because "it wouldn't have been appropriate."
Cheever said that Birchmore had been hospitalized in 2020 after saying she was going to hurt herself. At the time, she had been staying in her late grandmother's house and was upset because her aunt wanted to sell the home, Cheever said. But Cheever said she believed Birchmore wasn't seriously considering harming herself.
"Based on your years of knowing Miss Birchmore, did you think she was suicidal?" the prosecutor asked.
"No," Cheever responded.
The prosecutor asked Cheever about video showing Farwell wearing a mask. The prosecution said in its opening statement that Farwell was wearing a mask when he entered Birchmore's apartment building before she died, even though he was opposed to wearing one during the COVID pandemic.
"Did the defendant wear a mask when he was required to?" the prosecutor asked.
"I never saw him with a mask on," Cheever said.
During cross-examination, the defense called into question just how well Cheever knew Birchmore. Cheever said Birchmore never told her that she was pregnant.
"She told 85 people she was pregnant," the defense countered.
The defense also pushed Cheever on her assertion that Birchmore was not suicidal.
"She never said to me, Heather, I want to kill myself; those words never came out of her mouth," Cheever said.
The second witness to testify was Cheryl Carlson, a school principal in Auburn who previously hired Birchmore to be an instructional assistant working with students in Sharon. She said Birchmore was excited to tell her she was pregnant just before the holiday break in 2020.
"She said that the father was in a committed relationship and that there were children involved, and that the plan was that he was going to leave his situation when her child was born," Carlson said.
Carlson said she expressed concern, but Birchmore told her, "she wanted a baby to have someone to love."
The last day Birchmore came work was Feb 1, 2021, Carlson said. There was a snow day the next day, and Carlson said Birchmore didn't log on for virtual classes the next day. When she didn't show up to school on Feb. 4, the school requested a wellness check from police and Carlson was told she died by suicide.
"It didn't make sense to me," Carlson said. "Because she was so excited to have that baby, she was so determined to have the baby, it didn't fit with her character."
During cross-examination, Carlson said that Birchmore was telling third-graders that she was pregnant by her police officer boyfriend. She also said that Birchmore's pay was docked because she was taking more sick days than she had available.
Jurors were shown graphic crime scene photos of how officers found Birchmore during a wellness check.
Canton Police Department school resource officer Ensley Cotard testified that he and another officer saw her on the floor with a strap around her neck, hanging from a door knob. Cotard said he called his supervisor.
"I advised him that it appears to be a suicide," Cotard said.
In cross-examination, Cotard said he had previously seen a suicide where the person was in a seated position. He also said he didn't notice any signs of a struggle at the scene.
Prosecutors said that when Birchmore died, she was pregnant with what she believed was Farwell's child.
"At that point, the only thing that we thought of is that Matthew Farwell murdered her," Lauren Andrews, the mother of one of Birchmore's closest friends, told CBS News. "It was complete one hundred percent exploitation is what it was. It was grooming and then the passing her around to other police officers."
Farwell's attorney did not deny her client and Birchmore had an affair, but she said Farwell never thought the baby was his and when he broke up with Birchmore, she killed herself. The defense said in a court filing that DNA testing confirmed Farwell was not the father.
The prosecution said Birchmore eventually started to realize Farwell's behavior was wrong and threatened to expose him unless he agreed to give her a baby.
"She could end his life with the information she had, so he was going to end hers first," prosecutor Torey Cummings said in opening statements Friday. The prosecution said Farwell strangled Birchmore on February 1, 2021 and staged it as a suicide.
Farwell is charged with one federal count of killing a witness or victim and faces a mandatory sentence of life in prison if convicted at his trial in South Boston. He also faces a charge of causing the death of an unborn child. He has pleaded not guilty to both.
"Matthew Farwell did not kill Sandra Birchmore. He did not," his attorney Kimberly Stevens said in opening statements.
Over the weekend, prosecutors filed a new motion asking that the jury hear about three other alleged affairs that Farwell, a married father of three, had. They claim the other affairs are evidence that Farwell took extra steps to hide his relationship with Birchmore.
Andrews said Birchmore was excited about becoming a mother.
"She made a really strong decision that she was going to go to nursing school, and she had applied to nursing school," Andrews told CBS News. "There is absolutely no way I can tell you from my heart that that woman was going to commit suicide."
Sixteen jurors - 10 men and six women - have been seated for the trial, which is expected to last about five weeks.
No cameras are allowed in federal court so the trial is not being livestreamed or broadcast.
