The wife of an NYPD officer assassinated in Harlem 47 years ago is getting ready to demand — again — that her her husband’s killer remain behind bars.

“Tomorrow morning, when I give my statement, my mind will be back in 1971,” Diane Piagentini told The Post from the Deer Park home she once shared with her husband, Joseph. “My two daughters will be here and we will give our statements.”

Herman Bell, who is serving 25 years to life, has in the past insisted that he has expressed remorse for the shooting deaths of Officers Piagentini and Waverly Jones and has been a model prisoner. But the widow said she still believes the killer would have hate in his heart for cops.

Bell was one of three men to gun down Piagenti and Jones. One accomplice died in prison and the other is up for parole in June.

“Even though they are older, and they’ve been in prison for long time, I do feel like the rhetoric of the 1970s is still embedded in them. If they do come out, that is not going to go away,” Piagentini said.

Her two daughters were 3 and 1 when he was killed. Today she has two grandchildren he has never met.

“To this day, I still miss him,” Piagentini said. “He loved his job. He worked in Harlem. He was on the street. He was a very caring man.”

PBA president Patrick Lynch insisted that Bell should stay in jail in part because of the way the men plotted killing the officers, making a phony call to get them to respond and then shooting them from behind, killing Jones on the spot.

“PO Piagentini was wounded on the ground and pleaded for his life telling his attackers that he had two young daughters to live for,” Lynch said. “Bell and his partners then emptied both officer’s guns into PO Piagentini.”