From Left: with former partner Justine Sadokierski and Robert Kennedy Jr. 1998, with Donald Trump in 1991.

Despite having no knowledge of guerilla war, Monte was soon embroiled in one. One day, while sitting in a four-wheel drive in the desert listening to the 'dismal strains of Send in the Clowns," he and his men were caught in an ambush. The shooting stopped and the smoke lifted to reveal an apocalyptic scene.

"The air was thick with gunpowder and the smell of death," writes Monte. "We'd lost 12 men, and that many again were wounded and crying out in great pain. Just under 50 of the raiders were dead, including Prince Ahmed, the treacherous member of the ruling family. Any wounded raiders who had survived the battle had been finished off by our men. There was no Geneva Convention here. The rule of the desert was the same as the rule of the jungle, and this was literally a no-man's land."

The money and the publicity Monte received from his Dubai exploits changed his life, at least on the outside. He bought a Rolls-Royce, a solid gold bracelet, and decided that he would look "top shelf".

Like most of Monte's decisions, it was part business, part personal - the flashy cars and jewellery attracting the rich clientele he sought, while meeting his own needs to be seen as successful and wealthy. On the day of our interview, Monte has parked his dark blue Rolls-Royce illegally but prominently outside the building, preferring to suffer a parking fine for the sake of convenience and image.

It is an image which has also helped create enemies. "He gets a lot of grief from his competitors, not to his face but behind his back," says David Cox, a PI and manager at the Australian College of Private Investigators in Sydney. "A lot of those guys are running around chasing Mr. and Mrs. Jones on infidelity cases and he is running around chasing sultans and sheikhs - you'd be a bit annoyed."

Monte's desire for money ad recognition has seen him gravitate naturally to the media. "I think I've been written up 1200 times," he says confidently, as if he has notched up a count on his bedroom wall. Monte hires publicists, issues press releases and cultivates media contracts.

"Some of the stuff that he has done is not that incredible if you are in the business," says one PI who asks not to be named. "It's just that he talks about it and we don't." Why? "Publicity is crucial to business," says Monte. "While to the outsider I might be partying and trying to attract the press, in reality I'm securing my next case."

By the late '70s, Monte's cases were getting stranger. The days of chasing clandestine lovers through the suburbs had been replaced by cases fueled by the weird whims of the fabulously rich.

In 1979 Monte was approached by a representative of the Rockefeller family to search for Michael Rockefeller, heir to one of the world's biggest fortunes, who went missing in the jungles of Irian Jaya in 1961. The disappearance of the 23-year-old Rockefeller, who had travelled to Irian Jaya to collect artefacts to display in New York's Metropolitan Museum of Art, was one of the great mysteries of the time. The most common theory was that Rockefeller's rickety boat capsized in the remote Asmat region while he was attempting to take a sea route from one part of the coast to another. He tried to swim ashore and was never seen again.

For four months Monte investigated the case and came up with nothing. Then one day, he says, a nun came to his door and said that her brother, who had been a missionary priest in Dutch West New Guinea, knew the real fate of Rockefeller.

Monte strapped the nun to a lie detector and when she passed, he scurried off to Amsterdam to the priest. The priest told him that Rockefeller did not drown, but was killed by a tribe of Asmat people after he tried to steal a sacred skull pole.

When Monte told the Rockefellers the story, they asked him to find Michael's skull. He packed several white linen suits, some Havana cigars and ventured into what he calls "crocodile-infested head-hunter land". His lurid version of his boat trip into the jungles of Irian Jaya with a band of rogue Indonesian soldiers is ripped straight out of Conrad's Heart of Darkness. "Each kilometre up the river made us somehow more primitive," he writes. "As if we were journeying into the dark heart of our own soul."

Occasionally his band of soldiers would stop at a village and shoot the inhabitants. On one occasion, as Monte and his men were walking through the jungle, he says they came across a tribe of "warrior headhunters" ready for battle. "The warriors wore nothing but penis gourds," writes Monte. "Some had their hair decorated with long bird plumes, most carried spears and shields."

The fight was over in minutes. "With the air thick with the smell of blood and cordite we checked the damage," writes Monte. "Eight natives dead, one commando speared badly.... at times like this I thought constantly of my sons at home."

Monte says his search ended when he made contact with a chief deep in the jungle who repeated the priest's story. "His predecessor, now dead, had killed Rockefeller," writes Monte. The tribe claimed that they had Rockefeller's skull along with those of two other white men they had killed. Monte traded an outboard motor for all three skulls and fled.

Weeks later, Monte says he found himself in the Rockefeller family's luxury apartment on New York's Fifth Avenue signing papers promising to keep silent about the case for ten years. "I asked [Rockefeller lawyer Albert Gross] if they had identified a skull as Michael's," he writes. "Gross confirmed that they had."

By the 1980s, Monte's Sydney business was booming. He began working for big corporate clients, including property group Westfield. Monte also kept more questionable company. "He used to have some of the heaviest people in the city as his bodyguards," says one PI. "At his parties there would be society types, barristers and crims, all mixing together."

Yet despite his high-flying existence, Monte's personal life was a mess. His first marriage was a disaster from the start, with Monte and his wife living separate lives soon after the birth of their two boys, Adam and James. By the time they divorced in 1985 Monte was raising the boys by himself.

Even in the rugged world of PI's, this won Monte some brownie points. "He brought the kids up on his own," says Bob Lee. "A bloke was after him [to kill him] at the time, and we thought it was pretty low to try and knock off a bloke under those circumstances."

Monte survived the hit men but barely survived his ex-wife, who accused him of trying to murder her. The case never reached trial, but the fallout and bad press drove Monte overseas. "None of my so-called friends were talking to me," recalls Monte, who says he became a social leper. "Everywhere I went there was 'ah mate, you shouldn't have tried to kill you wife' and all this kind of shit. It cost me half my business." And, he says, his kids had to leave Scots College, the exclusive Sydney private school. Monte's bitterness is still palpable - the chapter in the book about his ex-wife had to be toned down for legal reasons.

In 1990 he fled to Los Angeles with his new lover, Justine Sadokierski, a rookie PI half his age. They set up shop and Monte soon had Gregory Peck, Julian Lennon and Diane Keaton, among others, on his client list. Eventually, he says, "Justine and I ended up sharing sushi with the likes of Heidi Fleiss, Billy Zane, Shannen Doherty, Mick Jagger, Billy Joel, Jack Nicholson and Christie Brinkley."

Despite this, Monte says the business never took off and he moved to New York, setting up the Monte Investigation Group in - of all places - the Rockefeller Center. "When I finally settled in Manhattan in the mid - 1990s it seemed, for the first time in my life, that I'd arrived where I truly belonged, home," he writes. "I was instantly accepted socially and professionally without all the baggage that had encumbered my life over the years."

Monte began winning corporate and celebrity work. Soon he was turning up on TV and radio chat shows. The world's most public private investigator had fallen in love with the world's media capital - it was a marriage made in prime time.

As he gets older, Monte is increasingly sour about his profession. "I don't particularly like anybody in my business, I don't have friends in the business," he states. "They're so proud of serving documents on you, like, 'I caught you!"

Indeed, the longer Monte talks, the more unhappy he seems about his life, which he says has been emotionally stunted. "I don't know the bloke who was going around in the early '70s," he says. "He didn't know how to cry and was very proud of that fact. All I was thinking was how to be a survivor, how to make a lot of money. I wasn't immoral, I was just looking at how to get up there quickly.

"I think my parents f...ed up my emotions a long time ago. In my first 20 years I was never going to get love or attention so I said 'How do you live without that?' - I saw the world without any need for emotion."

Could it be that after all these years and all those bullets, Monte is discovering his soft side? "He's not a mean bloke, he's a professional," says one PI who asks not to be named. "If I had to get my kids found or some serious job, I don't reckon he'd charge me. He's doing a job for free at the moment for someone, which we won't do because it's too dangerous."

Monte has come to see his life as a sort of accidental adventure - a well-armed search for meaning for a man who has convinced himself he is a gentle soul. "I had to find out [about life] in a stilted way," he says. "I had to get to the other side without getting hurt or hurting too many people along the way, but it wasn't as if I was looking for it. I'm not the mercenary type; I always wanted to be an English or an ancient history professor. I think I'm extremely shy."

The Spying Game, by Frank Monte (Pan Macmillan, RRP $30), published July 4.