One of the New York Police Department’s most frustrating unsolved cases dates back to 1971 and the shooting death of Robert Bolden, an off-duty police officer in Brooklyn.

According to the New York Post, the agency has cobbled together a record reward sum of $111,500 in their search for tips that might solve the case.

Bolden was a veteran of the U.S. Navy before becoming a cop in the borough’s 75th Precinct. He was reportedly trying to break up a fight at a bar when someone opened fire with a sawed-off shotgun, killing the 15-year police veteran.

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For current NYPD Detective John Bolden, the motivation hits even closer to home.

“I never met my grandfather but he is the reason I became a cop,” he said.

The fallen officers grandson went on to say he heard stories growing up about “how he loved being a police officer, how he loved helping people in the community and how he was always working, even when he was off duty trying to help people.”

As part of a continued commitment to help the younger Bolden solve the family crime, Crime Stoppers is planning a media campaign to raise awareness of the case.

Those with information related to the case are encouraged to contact Crime Stoppers by calling 1-800-577-TIPS.

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[Featured image: Robert Bolden, NYPD]