The family of a Massachusetts bodybuilder who died after police used a Taser on him as he allegedly attacked a Tinder date with a knife said he had been undergoing mental health treatment.

Erick Stelzer died Thursday after police responding to a domestic disturbance call found him "actively assaulting" a woman with a knife and shocked him with a stun gun in order to free her, according to the Cohasset Police Department.

Stelzer, 25, was provided medical treatment after he was struck, but became unresponsive on the way to the hospital and was later pronounced dead, police said.

The woman, identified by her family as Maegan Tapley, was also taken to the hospital where she was treated for multiple stab and slash wounds but was expected to survive.

A GoFundMe page set up for Tapley said she would need "many surgeries," adding that in addition to sustaining cuts, most of her hair was ripped from her head in the attack.

Erich Stelzer via Instagram

Tapley and Stelzer had met on Tinder, her mother, Susan Tapley, told NBC Boston. She didn't say how long they had known each other.

An attorney for Erich Stelzer's family, Philip G. Cormier, told NBC Boston that Stelzer had been suffering from delusions, erratic behavior, and extreme paranoia and had been in the care of mental health professionals for about a month.

Cormier said Stelzer's family became increasingly concerned for him on Christmas Day and called EMTs because they feared he was having a psychotic breakdown. The EMTs told the family that Stelzer didn't need to be hospitalized because he was "lucid enough to know his own name and the date.''

The family said that on Dec. 26, they were putting plans in place to send Stelzer to an inpatient facility, but the attack happened before they could send him.

Stelzer was a bodybuilder who frequently posted weightlifting and diet advice videos to YouTube and Instagram. His father, Harold Stelzer, said his son was 6'8 and 300 pounds, but he believes the police officers' use of the taser was "excessive."

“I know that one hit is substantial. Two will knock you down. There were four cops there. Can’t they handcuff him?” Stelzer asked.

The Norfolk District Attorney’s Office and the Massachusetts Chief Medical Examiner are investigating the death.