PITTSFIELD, Mass. - The Berkshire District Attorney's Office found Pittsfield police officers acted in self-defense when they fatally shot Miguel Estrella in March, officials said Friday.

Berkshire District Attorney Andrea Harrington said at a news conference outlining the investigation's findings that officers Christopher Coffey and Nicholas Sondrini responded to calls on the night of March 25 of a person going through what appeared to be a mental health crisis.

When the officers arrived, they found Estrella, 22, in the street holding a large kitchen knife. The officers instructed Estrella to drop the knife and attempted to deescalate the situation verbally. 

Estrella then began advancing toward officers with the knife and, after the officers unsuccessfully attempted to use tasers to stop him, Sondrini shot him twice.

Harrington said the knife Estrella was carrying constituted a threat to the officers' safety. She called the incident tragic, but not criminal.

"The facts discovered during the course of this investigation do not establish probable cause to charge the officer," said Harrington. "Nor would the Commonwealth be able to fill its burden of proof beyond reasonable doubt required for a criminal prosecution."

Harrington also called on lawmakers to take immediate action to provide more mental health services in the area.

Estrella's sister, Elina Estrella, spoke at the news conference on the family's behalf, saying her brother's death was the result of systemmic issues when it comes to dealing with a mental health crisis. 

"We need to do better," she said. "We need to answer these questions so that this doesn't happen to anyone else. Miguel was a kind, big-hearted, complicated son, brother and moreso to many of us."

The officers had responded to the same scene earlier in the evening along with EMS responders, but Estrella declined medical treatment for self-inflicted cuts on his face and the officers departed.

A Pittsfield Police Department internal investigation in April found Coffey and Sondrini did not violate the department's policies.