Nov. 19, 1961: Two young men drift on an overturned catamaran along the coast of southwest New Guinea. Twenty-four hours have passed since their motor died.

One of the men, Michael Rockefeller, 23, the son of New York Gov. and future Vice President Nelson Rockefeller and scion to one of the richest families in America, decides to swim 10 miles to shore.

This is the last time Michael Rockefeller is seen alive.

The official cause of death would later be listed as drowning. The prevailing theory was that he was consumed by sharks.

They got one thing right: Michael was eaten. But it wasn’t by sharks.

‘Death doesn’t just happen’

“Savage Harvest,” a new book by veteran travel writer Carl Hoffman, makes the compelling and convincing case for the true story behind his disappearance.

The series of unfortunate events that led to Michael’s death began auspiciously on Feb. 20, 1957, when Gov. Nelson Rockefeller, grandson of Standard Oil founder John D. Rockefeller, one of the richest men in the world, opened the Museum of Primitive Art at 15 W. 54th St. It was billed as “the first . . . of its kind in the world.”

Michael, 19 when the museum opened, became one of its board members. “It’s easy to imagine the power the event had over him,” writes Hoffman.

Michael wanted to gather artwork for his father’s museum, but without going through intermediaries. A natural adventurer, he would go right to the source.

Aware of the untouched world of Asmat in Dutch New Guinea, a place known for its intricate woodcarving, Michael made plans to scout out a location there to do some art-hunting.

In October 1961, Michael traveled to Asmat with anthropologist Rene Wassing. Carrying bartering goods like steel or tobacco — which the Asmats had become addicted to — he visited 13 villages in three weeks, never spending more than three days in one location.

He gathered hundreds of items, among them bowls, shields, spears and the most prized possession, four sacred bisj poles, spiritual artifacts that are often dedicated to the deceased, which now hang in the Michael C. Rockefeller Wing of the Metropolitan Museum of Art.

The scavenging trip was a success. But one trip wasn’t enough.

The Asmats, cloistered from the outside world since the first inhabitants arrived at least 40,000 years before, lived without steel, iron, paper or roads, relying solely on wooden canoes to traverse the Arafura Sea.

Unlike the remote peoples of the Amazon, they were not buttressed by the deep jungle. They lived right next to the coast along a main waterway, but since their lands offered little in the way of natural resources or substantial game, they were largely left alone.

The Asmats were agile, quick and muscular from paddling. They were naked except for a tight band of rattan just above their knees. Western taboos did not exist here.

Men had sex with men. They shared wives and practiced polygamy. They sometimes drank each other’s urine and covered themselves in human blood during bonding rituals.

This was a “complex spiritual world balanced by ceremonies, ritual and reciprocal violence,” writes Hoffman.

“No death just happened. Even sickness came at the hands of the spirits.”

This spirit world centered around the practice of headhunting and its outgrowth, cannibalism. A founding story of the first brothers in the world described how to exactly butcher, eat and honor a human.

Cannibalism was not about getting protein.

“Headhunting and cannibalism were as right to them as taking communion or kneeling on the carpet facing Mecca,” he writes.

When Michael Rockefeller arrived, times were changing. The Dutch, who had taken over the archipelago from the United East India Company in 1800, had been paying more attention to their redheaded stepchild of a colony.

The Dutch government had even named a new man, Max Lapré, known for his “firm hand,” to oversee the colony.

Under Lapré’s command, five elite Asmats were gunned down.

In a world where death requires death, where retribution is vital to placating the spirits, the natural order had been upset.

“The world was out of balance, an open wound festering in the village each and every day, even more so because Lapré was a white man,” writes Hoffman.

This was the world that Michael swam right into on Nov. 19, 1961.

“He was alone, he was the least powerful. They respect power. And I think he was in the wrong place at the wrong time,” Hoffman says.

‘Now is your chance’

Though Hoffman will never know the exact details of Michael’s death, he believes that his account in the book is the closest we’ll get with the information available.

Michael would have been exhausted after swimming 10 miles from his boat to land.

According to various interviews with villagers, the Asmats first mistook him for a crocodile.

“No,” said one of the men, named Fin. “It is a man.”

The group surrounded him. One person said: “Now is your chance.” It was a chance for retribution for Lapré’s raid; it was a chance to vent frustrations over their changing world; it was a chance to restore balance.

One of the men drove a spear through Michael’s ribs. With one blow of an ax to the back of his head, he was dead. The ritual would now begin.

According to documentation on the Asmat headhunting ritual, they would first remove Michael’s head, then slit him from the neck down his back. Entrails would be removed. Legs and arms would go into the fire while the group chanted. His charred body parts would be passed around for everyone to taste.

His blood, which they saved, would be smeared over their bodies. Once the head was fully cooked, they would scalp it, remove his brain and eat it.

Everything not eaten would be saved. Some would be used in weapons, others as religious icons.

“If they’d killed Michael, that was how it had been done,” Hoffman says.

If Michael drowned, his body would have been recovered by search parties; he’d had two empty gasoline tanks tied to his belt, which were never found; and, adds Hoffman, sharks rarely attack humans, and there had never been a shark attack death in Asmat.

‘Where is his head?’

Once news of Michael’s disappearance hit the outside world, the Dutch deployed armies of ships, crews and airplanes to search for the young man with such an important name.

The Rockefeller family boarded a series of flights to New Guinea, spending over a week helping with the search mission. Even President John F. Kennedy sent condolences and offers of support.

But “all the tools of the rich and privileged had been useless” in Asmat, Hoffman writes.

By the ninth day, Michael’s family flew home. After a month, the Dutch had called off the search, ruling his death a drowning.

At the same time, Dutch Catholic priest Hubertus von Peij, who had spent years living among the Asmats, traveled to the village of Omadesep in New Guinea. Out of the few white men who had spent time in Asmat, von Peij knew it best.

Hoffman tracked down von Peij for this story. The man is still alive, living in the Netherlands. He had never before spoken publicly.

A month after Michael’s disappearance, the priest was approached by four Omadesep men, who had witnessed the ceremony. They wanted to confess.

“Was he wearing glasses?” von Peij asked. “What kind of clothing was he wearing?”

Their answer was sobering. “The white man was wearing shorts, but shorts they’d never seen before . . . Underpants.”

“Where is his head?”

“It hangs in the house of Fin. And it looks so small, like the head of a child,” they said.

With their confession, the priest wrote to his superior, who was so convinced by the evidence that he wrote a long report to the controller in all caps:

“IT IS CERTAIN THAT MICHAEL ROCKEFELLER WAS MURDERED AND EATEN BY OTSJANEP.”

The governor of Dutch New Guinea sent a “secret” cable to the minister of the interior. Hoffman recovered this document, though it was marked “Destroy.”

It was a bad time politically for this type of news. The Dutch were fighting the UN for their half of New Guinea, which was in the process of being given to Indonesia.

It was a classic coverup.

“I wrote my bishop and he forbade me to talk, to tell the story,” said von Peij. “The government felt ashamed.”

Hoffman believes that the Rockefellers never knew about this information — beyond an AP wire story that recounted the news, leaked by a gossipy priest, that Rockefeller was killed and eaten by the Asmats.

After the Dutch government denial, the newspaper rescinded its version, saying there was no truth to it.

Rumors have persisted to this day. And they have ranged from the strange to the absurd and have become the subject of plays, articles and books.

As for the Rockefellers, they have not accepted any other version of events than that Michael drowned. No Rockefeller has ever been back to Asmat.