HARLEM, Manhattan (PIX11) — Exactly 50 years after patrolman Phillip Cardillo responded to a 10-13 call coming from Mosque #7 on W. 116th Street, a call that ended with his shooting death, the slain cop finally received formal acknowledgement in the Harlem community for his sacrifice.

Cardillo’s youngest son, Todd — who was only a year old when his father was shot — was at the 28th Precinct Thursday as a street sign was affixed to the precinct’s facade in Cardillo’s memory.

“It’s part of the history of this city, and they have to know what happened,” Todd Cardillo told PIX11 News.

Earlier Thursday, scores of active and retired police officers were part of a motorcycle and police vehicle procession that visited Phil Cardillo’s gravesite at Calvary Cemetery in Queens.

The street sign in Harlem was a sensitive issue for Community Board 10, which argued a decade ago that a traditional sign would open old wounds there.

“It was an assassination,” said Rodney Harrison, now the Suffolk County Police Commissioner, who served thirty years in the NYPD and once commanded the 28th Precinct.While leading the precinct, Harrison had tried to persuade the Community Board to install the sign honoring Cardillo near the stationhouse.

The shooting of Cardillo on April 14, 1972 remains one of the most politically-charged cases in the history of the NYPD.

At the time, Mosque # 7 was run by Nation of Islam leader, Louis Farrakhan, who flew into a rage that police officers were inside the location after a phony 10-13 call was made that day from the site.  10-13 signals a police officer is in trouble.

One of Cardillo’s colleagues, Rudy Andre, said when he arrived at the mosque, the front door was “dead-bolted” and he saw Cardillo and other cops being beaten inside by mosque members.

When police officers managed to breach the front doors, Andre said he realized someone had shot Cardillo in the torso with his own police gun.

“And I said, ‘Philly, you’re gonna be alright,” Andre recalled.

But Cardillo, a 31 year old father of three from Astoria, was not alright.He died six days later from his wounds.

In the immediate minutes after the incident, Rudy Andre said he and other cops chased mosque members to the basement, hoping to find the person who shot Patrolman Cardillo.

“Where his blood was, there was a mop and they were cleaning up,” Andre said, something that corrupted the crime scene.

When Louis Farrakhan turned up, along with then-Congressman Charles Rangel and Ben Ward, who was an NYPD Community Affairs executive at the time, the 16 people who were rounded up in the basement were allowed to go and told to show up at the local precinct later for questioning.  They never did.

Meantime, there was a melee outside the mosque, with police cars getting overturned and some cops getting hit by bricks and bottles.

“I thought I was shot,” said retired Detective Randy Jurgensen, who later wrote a book about the incident called “Circle of Six.”

The book focused on the six people in power who made decisions that negatively impacted the criminal case.

Phillip Cardillo’s shooting never yielded any convictions, as the one suspect Jurgensen arrested two years later was acquitted after a second trial.

The case stirred so much anger within the NYPD and in Harlem that then-Mayor John Lindsay and former Commissioner Patrick Murphy didn’t attend Patrolman Cardillo’s funeral.

In 2015, after extensive reporting by PIX11 News, former Police Commissioner Bill Bratton named the street outside the new Police Academy in College Point, Queens after Patrolman Cardillo.  Earlier that same year, a new police boat was christened in Cardillo’s memory.  There’s also a canine dog in transit who bears the name, Phil Cardillo.

Now, on this 50th anniversary of the infamous shooting, Patrolman Cardillo’s sacrifice received official acknowledgement in the community where he served, and died.

The city’s new Police Commissioner, Keechant Sewell, spoke at the ceremony Thursday outside the 28th Precinct in West Harlem.

“While we cannot right all the wrongs that occurred at that time,” Sewell said, “we can take another step forward to honor Patrolman Cardillo’s legacy.”

Todd Cardillo, who flew up from his Florida home, said his late mother tried to shield him from details of his father’s murder. He learned the truth when he was 20 years old.  

“Obviously, nobody really knows what happened, except the people that were in there.”

Watch: PIX11’s 2014 special on NYPD officer Phillip Cardillo’s case