It was one of the greatest disappearing acts of modern times. Amidst a swirl of allegations and rumors that the Nugan Hand bank was involved in arms smuggling, drug-running, and covert operations for the CIA, the institution’s American founder vanished from Australia. Thirty-five years later, that man, Michael Jon Hand, was tracked to a small town in Idaho where he has been living under the name of Michael Jon Fuller.

Hand was found by an Australian writer, Peter Butt, whose just-released book, “Merchants of Menace,” discloses Hand’s whereabouts after decades of mystery.

If finding Hand, now 73, solves one mystery, it raises another. How could he have lived in the United States so long without being detected? He changed his name only slightly, from Hand to Fuller, and did not get a new social security number, according to Butt.

Hand’s company, G.M.I. Manufacturing, is registered with the Idaho Secretary of State. The company “now manufactures tactical weapons for US Special Forces, special operations groups and hunters,’’ Butt wrote. Has Hand/Fuller been brazen, foolish, or, as Butt asks, does he belong “to a protected species, most likely of the intelligence kind?”

Two years after fleeing Australia, in 1982, when the CIA was involved in a covert operation to overthrow the left-wing Sandinista Government in Nicaragua, Hand was working as a military adviser in the region where the anti-Sandinista “contras” were based, according to an Australian intelligence document, which was declassified earlier this year.

The FBI did not immediately respond to a request for comment. The CIA has previously denied that it had any links to Hand.

Hand had been a Green Beret in Vietnam and a CIA operative in Laos, before moving to Australia, where he and Frank Nugan, a wealthy playboy, established the Nugan Hand Bank in 1973, with $80. Hand fled Australia seven years later after Nugan was found dead inside his Mercedes Benz, his left hand holding the barrel of a .30-calibre rifle a few inches from his head, his right hand near the trigger.

During an inquest into Nugan’s death, Hand testified that the bank was insolvent, owing investors (large and small) some $50 million. The inquest ruled Nugan’s death a suicide, a finding that many Australians found dubious.

With depositors and law enforcement authorities in pursuit, Hand, with assistance from a former CIA officer, secured a forged Australian passport, donned a false mustache and beard, and fled Australia in June of 1980. He flew to Fiji, then on to Canada, from which he could cross into the United States without a visa.

The Sydney Morning Herald first reported on Butt’s findings on Monday. In a segment that aired Sunday night, Australia’s “60 Minutes” filmed Hand/Fuller emerging from a pharmacy at a shopping mall in Idaho Falls. He has a full beard, neck brace, and was wearing sunglasses and a blue checked shirt. He refused to answer any questions, or speak any words, when confronted by “60 Minutes” reporter Ross Coulthart.

Suspicions about the bank’s links to the CIA arose almost immediately after Nugan was found dead. His wallet contained the business card of William E. Colby, who had been director of the CIA from 1973 to 1976.

Colby was forced to resign when it was reported that the agency had been engaged in illegal spying on American citizens. He became a legal adviser to Nugan Hand, and on the back of his business card were handwritten dates when someone, presumably Colby, would be in Hong Kong and Singapore.

As reporters began digging into Nugan Hand, they found that Colby wasn’t the only individual with an intelligence or military background involved with the bank.

“Nugan Hand had enough generals, admirals, and spooks to run a small war,” Jonathan Kwitny, an investigative reporter at the Wall Streeet Journal wrote in the definitive book about the bank, “The Crimes of Patriots: A True Tale of Dope, Dirty Money, and the CIA.”

The president was a retired Navy Admiral; the head of the Manila branch, a retired Air Force general; the head of the Washington office, a retired Army general; another retired army general ran the office in Hawaii.

In a review of Kwitny’s book in the New York Times, Howard Blum asks: “Why were so many honorable men working for such a blatantly corrupt organization?”

Several former CIA operatives also had links to the bank of one kind or another, including Frank Terpil and Edwin Wilson, who were indicted for selling explosives to Libyan dictator Muammar Qaddafi. (Terpil fled to Cuba, where he still lives. Wilson, who was convicted and sentenced to prison, died in 2012).

In Australia, the collapse of Nugan Hand was the subject of several high-level investigations in the 1980s. They found, generally, that the bank was engaged in money laundering, tax evasion, and violation of Australian banking laws. One investigation found links between Hand and the CIA, while another did not. At the time, Australian investigators complained about the lack of help from the FBI

Hand, who was raised in the Bronx, studied forestry for a year before enlisting in the Army in 1963. He was sent to Vietnam, where he was awarded a Purple Heart, Silver Star and the Distinguished Service Cross, the second-highest combat medal. At some point, he became a contractor operative for the CIA, and did work with Air America, the agency’s front airline, according to one of the Australian investigations.

He visited Sydney on “R & R,” — “rest and recuperation,” the once-yearly out for American soldiers in Vietnam and eventually emigrated. He hung out at the Bourbon and Beefsteak Bar, in King’s Cross, Sydney’s seedy vice district (then and now), where he met Frank Nugan. They began selling real estate, primarily to American servicemen in Southeast Asia, then trading in silver bullion, before opening the bank.

Nugan wrote the bank a check for $980,000, then covered it by writing a bank check to himself for the same amount. “Through this elementary accounting fraud, Nugan could claim that the company’s paid-up capital was a million dollars,” Alfred W. McCoy writes in “The Politics of Heroin: CIA Complicity in the Global Drug Trade.”

From those humble and corrupt beginnings, grew a global goliath that attracted investors with promises of 16 percent interest on deposits, in off-shore accounts. By 1979, Nugan Hand had 13 branches around the world, and many of its depositors were drug traffickers, according to Australian investigators.

Hand told colleagues that it was his ambition that the bank “become a banker for the CIA,” according to the findings of one of the Australian investigations.

Efforts to reach Hand were unsuccessful.