It was the score of several lifetimes — the Jan. 2, 1972, holdup of The Pierre. Eight men, armed and fearless, invaded the posh city hotel on a frigid morning and made off with $28 million in cash and jewels.

It was, says crime writer Daniel Simone, the greatest hotel robbery of all time.

Nick Sacco, a k a “The Cat,” is the last man alive who can tell the inside story of the heist. Now 76, he’s collaborating with Simone on a book tentatively titled “The Great Pierre Hotel Robbery,” which has already been optioned for a movie. Sacco has been in the federal Witness Protection Program for 40 years and agreed through Simone to tell his story for the first time to The Post.

It was all or nothing for Sacco and the rest of the crew that January day, even if the cops showed up. “We decided we weren’t going to give up. We were going to shoot first,” Sacco recalled. One police car passed the hotel while Sacco and the other hoods emptied its vault. The car did not stop.

Very little of the loot was ever recovered. Ringleaders Bobby Comfort and Sammy Nalo were the only robbers who served time — and Sacco says a bribe-taking Manhattan judge set them up to serve light sentences.

“The Lucchese family ran it. They gave us three cars, eight guns and three dozen handcuffs,” Sacco said. Comfort and Nalo, experienced thieves, directed the crew to hold three dozen hostages, mostly hotel workers, while they looted The Pierre’s vault. None of the hostages was injured. “We weren’t out to hurt anybody,” Sacco said.

The gang was long gone by the time police were called. The Luccheses arranged to destroy the getaway cars and the rest of the evidence.

“We got rid of everything,” Sacco said. “There was no way to trace anything back to us.”

The Pierre, at Fifth Avenue and 61st Street, is the city’s most elegant hotel. A mix of guest rooms and co-op apartments, it has been home to the likes of Aristotle Onassis, Elizabeth Taylor and Yves Saint-Laurent. Sacco’s compatriots carefully researched the hotel’s rules and the staff’s habits and learned it locked its doors overnight. The only way in was a reservation. So the robbers booked a room under the name Dr. Foster.

‘The Lucchese family ran it. They gave us three cars, eight guns and three dozen handcuffs’ - Nick Sacco

One robber, dressed in a chauffeur uniform, drove up to the 61st Street entrance in a Cadillac limo just before 4 a.m. and announced Dr. Foster’s arrival. A security man called the front desk, which confirmed the reservation. He opened the door. The robbers put a gun to the guard’s head.

They made their way through the lobby to the front desk, where they abducted the night clerk. Sacco and others in the crew rounded up the rest of the staff at gunpoint. The workers were seated on the floor in a lobby alcove. “We ran out of handcuffs,” Sacco said. “We were short three or four.” They tied or taped up the extra hostages.

Comfort took over the phone at the front desk. “If we got any calls — say, somebody needed pillows, or whatever they might be — I would go up and give it to them,” Sacco said.

Except for the driver, the robbers wore tuxedos and disguised their faces with eyeglasses, fake beards, wigs and the like.

While Nalo and another robber pried open the vault’s safe-deposit boxes, a Brazilian hotel guest on an upper floor called the front desk and complained that he had been waiting 15 minutes for the elevator. Comfort told the man the elevator operator was indisposed — he didn’t say the operator was one of his hostages.

Two robbers went off to get the Brazilian and took him hostage. They asked who else was in his suite. He said that he was on his honeymoon, and that his wife was asleep in one room and his mother-in-law in the other. They became hostages, too.

In the lobby alcove, another guest taken hostage recognized the Brazilian man. She was his mistress. He had secretly brought her along on his honeymoon and had called the elevator so he could go to her room for a tryst.

The Brazilian’s bride wore “a tremendous solitaire diamond ring — it was beautiful,” Sacco recalled. One of the robbers moved to take it. The others stopped him. “We came here to open the boxes,” Comfort explained. They would leave the hostages alone.

An elderly guest taken hostage told the robbers he was suffering chest pains. Comfort learned one of the guests was a doctor. He was awakened, brought to the lobby and ordered to treat the man — and ended up a hostage himself.

Weeks before the robbery, Nalo and Comfort researched old newspapers at the New York Public Library for information about The Pierre’s guests. They used the names they found in the gossip columns to sort through index cards kept at the front desk that identified the owners of the vault’s safe-deposit boxes.

The information helped them find boxes belonging to the wealthiest guests and residents. “We knew, approximately, who patronized The Pierre,” Sacco said. Thanks to that knowledge and the cards, “the overwhelming majority of the boxes paid off.”

One box had $500,000, in bundles marked “$10,000,” “$20,000” and “$30,000.” Another had $3 million in $500 bills.

The hoods also found boxes of jewelry. Probably the most valuable item was a $750,000 Harry Winston diamond necklace that belonged to Baroness von Langendorff. She still has a residence at The Pierre. A woman who answered the phone in her suite last week asked why anyone would be interested in a 44-year-old crime.

After a little more than two hours, the robbers had four suitcases filled with loot. “We had at least 75 to 100 boxes we didn’t open,” Sacco said. It was time to leave, but Nalo wanted to open one more box he thought belonged to a princess. “He was obsessed with these princesses,” Sacco recalled. “I said to him, ‘Listen, Sammy, we got four suitcases, money, jewels and everything. Buy yourself a princess.’ Everybody started laughing.”

Comfort had one last task: He told the hostages to wait before they called police. He gave a $20 bill to each hostage who was a hotel employee. It was “hush money,” Sacco recalled. “Nobody ever said anything.” Sacco says he has read transcripts of investigators’ interviews with witnesses, and they all misidentified the robbers.

The robbers made sure to leave by 6:45 a.m., before The Pierre’s day shift began at 7 a.m.

Sacco said he had little trouble getting rid of his share of the loot.

He and his compatriots had contacts in the city’s jewelry districts, on 47th Street and, in those days, Canal Street. They found experts who ground away any identifying marks on the gems they had swiped. “So we would lose half a carat,” Sacco said. They didn’t care. The stones were set into new rings, necklaces and other settings and sold to jewelers across the country.

The $500 bills were another problem, as the denomination was taken out of circulation in 1969. “It took a few weeks,” Sacco said. They eventually found jewelers, bankers and other businesses to take them. Sacco personally pocketed $2 million.

The heist made headlines for weeks, but media accounts of the time said the men got away with $3 million, far less than the $28 million Simone believes was taken. Simone offers several reasons for the disparity. One is that Comfort and Nalo didn’t disclose the full size of their take because they didn’t want to share it all with other criminals. Another is that they simply may not have realized the value of some of the jewelry. And the wealthy victims of the robbery may have had reasons for not fully reporting their losses. How do you explain to the IRS $3 million in a safe-deposit box?

Von Langendorff’s necklace ended up in the hands of a Detroit mobster who was an FBI informant. That led the NYPD to arrest Comfort five days after the robbery. Nalo was pinched a day after that. They took a plea deal to a burglary charge — a big reduction from armed robbery and a host of other charges that could have arisen from gunpoint hostage-taking. Sacco says the plea deal was arranged via a $500,000 bribe to Manhattan Supreme Court Justice Andrew Tyler.

Tyler sentenced the men to seven years in prison, three years more than he had promised. But the seven-year terms were thrown out by the Appellate Division. Simone believes the seven-year term was a ruse by Tyler. By tossing the sentence and imposing the four-year term Tyler originally promised, the Appellate Division unwittingly affirmed the terms of the bribe while diverting attention from it, he said.

‘That type of money — I never would have had that type of money in my whole life. When you are born to poverty and you start making money, it’s different.’ - Nick Sacco on how he misses his days as a crook

Tyler died in 1989. In a 1976 case unrelated to the Pierre robbery, Tyler was convicted of perjury for giving false testimony about his relationship with a gambler and numbers runner. The conviction was overturned on appeal.

Comfort and Nalo each served 19 months in prison. Several people were charged with possessing property stolen at The Pierre, but the two men were the only ones charged in the robbery itself.

Comfort died of cancer in 1986, and Nalo was murdered in 1988. Three other robbers were also murdered, and two died of natural causes.

Sacco owes his longevity to the Witness Protection Program, which he entered in 1975 after telling authorities what he overheard in jail about a mob triple murder. He and Simone speak on the phone and share documents via Sacco’s post-office box in California. They’ve never met in person, and Simone is not sure California is where Sacco really lives.

Sacco is sorry his days as a crook are over.

“I get so lonely, and it’s so boring,” he said of his life today. “I miss it. That type of money — I never would have had that type of money in my whole life. When you are born to poverty and you start making money, it’s different.”