NEW YORK (CBSNewYork) — Bronx District Attorney Darcel Clark is asking for a special grand jury to be impaneled to investigate the fatal police shooting of a 66-year-old emotionally disturbed woman earlier this year.

Deborah Danner was shot at her Bronx apartment after she threatened a police officer with a baseball bat on Oct. 18.

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Clark said the panel will determine whether criminal charges should be brought against the NYPD sergeant involved.

“I have pledged to the people of the Bronx to conduct a thorough, fair investigation into this matter and I believe that presenting the evidence to a grand jury will best accomplish that goal,” Clark said in a statement. “It is important to determine exactly what happened in this tragic incident.”

Sgt. Hugh Barry, who fired the fatal shot, has been on modified duty since the incident.

Mayor Bill de Blasio called the shooting tragic and unacceptable.

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“It should never have happened,” de Blasio said a day after the deadly shooting. “The NYPD’s job is to protect life.”

Commissioner James O’Neill said the NYPD “failed” and that some of the proper procedures weren’t followed in this case. Officials charged that there were other options, including the Taser on Barry’s belt.

Police union officials criticized de Blasio and O’Neill, charging that they rushed to judgement.

As CBS2’s Dana Tyler reported, on Monday, Sergeants Benevolent Association President, Ed Mullins released a statement saying, “We trust that District Attorney Clark will present the evidence in a far, reasoned, and judicious manner.”

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There is no timetable for the grand jury to be impaneled or for it to reach a determination, Clark said.