Man suspected in the killing of his ex-fiancee has a history of violently lashing out when scorned

• A Massachusetts woman was found dead in her truck and police have killed the suspect.
• Mary Anderson was reported missing Sunday and her body was found Tuesday in Vermont.

Mary Anderson, of Harvard, Massachusetts, was found dead in her truck Tuesday and the man wanted for questioning in her death was shot and killed by police a day later.

Vermont State Police say Anderson's ex-fiance Matthew Davis was wanted for questioning in Anderson's death and armed with a knife when he was killed.

"I cannot fathom what has unfolded these last few days. I am so lost and confused and mad," Ali Giannino, a friend of Anderson's, posted to Facebook. "Yes Matthew Davis has been shot and killed by police, but for me, honestly, this is not justice. There are so many unanswered questions I have."

Giannino told The Boston Globe on Wednesday that Anderson had ended her relationship with Davis months ago and he was not taking the break-up well, but the 23-year-old's friends never thought he was capable of killing her.

A missing license plate

Anderson was last seen alive in Hudson, New Hampshire, on Saturday, according to Vermont State Police.

On Sunday night, she was reported missing to the local police department, and on Tuesday her body was found in her truck in Brattleboro.

Giannino described herself to the Globe and on social media as like family to Anderson.

Starting on Sunday, Giannino began sharing photos of Anderson and Davis online asking for anyone who may know of their whereabouts to call the police. She wrote that Anderson had been "kidnapped" and a "Choose Life" license plate was removed from a family member's car.

When Anderson was found, she posted links to a memorial fund in her name.

"She was a beautiful soul, inside and out," Giannino told the Globe."She didn't deserve this."

When reached by Insider, Giannino said she would like to speak about Anderson, but needed time.

Vermont State Police said Davis was killed in a wooded area in Brattleboro, Vermont, after a detective doing a neighborhood canvas recognized him as the person wanted for interest in Anderson's disappearance.

Troopers and Brattleboro police fired their weapons, according to the statement.

A history of violence

The 34-year-old Fitchburg, Massachusetts, man had a history of lashing out when rejected.

In 2009, Davis was arrested after he snuck into the home of his ex-girlfriend — the father of his three children — and waited there overnight until she arrived with her new boyfriend, according to reporting in the Berkshire Eagle. Davis then stabbed the man, seriously injuring him, according to the Eagle.

The woman, who Insider is not naming, told the court at the time that Davis didn't like her dating other men, even though they weren't together.

Dale Eason, who was a Pittsfield Police Detective at the time, testified in court that Davis was affiliated with an unnamed gang.

Davis pleaded guilty to charges related to the attack, which included assault with intent to kill, and was sentenced to four to nine years in prison, according to court records obtained by The Globe. He was released on parole in 2015, and completed it two years later, according to The Globe.

According to the Justice Department, nearly, 15% of women and 4% of men in the US have been injured as a result of intimate partner violence, including rape, physical violence, and/or stalking by an intimate partner in their lifetime.

Women between 18 and 34 have generally experienced the highest rates of intimate partner violence, according to the DOJ.