In the week before Erich Stelzer died in police custody, after officers said they found him stabbing a 24-year-old woman, his family noticed a “decline in his mental health” and asked police to intervene, according to his mother’s lawyer.

“He was experiencing delusions, erratic behavior and extreme paranoia,” Philip G. Cormier, a lawyer for Diane Keiran, Stelzer’s mother, wrote in a statement to sent to MassLive on Saturday.

Stelzer, 25 of Cohasset, had been receiving treatment for an unspecified mental illness in the month leading up to the alleged attack, Cormier wrote in the statement. On Christmas evening at a family gathering it “became clear that his needs were not being met,” Cormier wrote.

His family called Cohasset police and EMTs to perform an assessment on Stelzer on Dec. 25. They believed he was having a “psychotic break” and needed to be hospitalized, Cormier wrote in the statement.

“The assessment by the EMTs was that he did not need assistance due to the fact that he was lucid enough to know his own name and the date,” Cormier wrote in the statement. “The family was surprised and unsure how to proceed.”

The next day Stelzer’s family hired a professional intervention team to help bring the 25-year-old to an inpatient facility for treatment, the lawyer said.

“Unfortunately, the events of Thursday night transpired before the intervention could be implemented,” Cormier wrote.

Police were called to Stelzer’s home on Church Street just before 10 p.m. Dec. 27 for a report of a disturbance. When they arrived police said Stelzer was assaulting a 24-year-old woman with weapons, including a knife.

A law enforcement official told The Boston Globe that Stelzer and the 24-year-old woman, who survived the attack, met on Tinder, a dating app, earlier in the week.

The Norfolk County District Attorney’s office said the woman sustained extensive stabbing and slashing injuries. The woman’s mother told NBC 10 her daughter would need plastic surgery and an eye specialist.

“In an effort to rescue the victim and disarm Stelzer, Cohasset police officers used tasers to subdue Stelzer,” the district attorney’s office said in a statement Friday. EMTs provided Stelzer with medical attention, but he became unresponsive on the way to the hospital, authorities said.

“The family of Erich Stelzer wishes to express its deepest sympathy for the victim and her family. They are without words to adequately communicate their grief and sorrow at the events that transpired, the physical and mental pain caused to the victim, and the loss of life of a young man who was someone's little brother and someone's son,” Cormier wrote in the statement.

Cormier said his firm was hired to “assist...in whatever facets we can.” It is not clear if the family plans to take legal action.

Cohasset police referred all questions about the incident to the Norfolk District Attorney’s office. The district attorney’s office did not immediately respond to a request for comment regarding Stelzer’s family’s claims on Saturday.