Police say Benjamin Walsh, 24, killed his girlfriend 20-year-old Olivia Bergstrom in their apartment on Saturday night.
He then drove to a Millis restaurant and stabbed his parents, police said. The family had been celebrating a relative’s 70th birthday.
Relatives were able to subdue Benjamin Walsh until help arrived.
Mike Walsh, the suspect’s father, told the Boston Globe that he feared the worst when he heard there had been a fatal stabbing in Needham. He said the family is “devastated” for Bergstrom and her family. He called the victim “the sweetest kid.”
Mike Walsh said his son has struggled with mental health issues and substance abuse.
The suspect’s mother is in serious condition — but is expected to survive.