It didn't take them long. Just hours after the collapse of the World Trade Centre on September 11, the internet's legion of pranksters got to work. First it was the stream of topical email "jokes" that follows every major news event. Then came the conspiracy websites blaming the attacks on everyone from the US federal government to Elvis. But two weeks in, an email started doing the rounds that seemed to grab the collective attention of bored office workers the world over. It contained the extraordinary image of a tourist posing on top of the twin towers, unaware of the plane looming behind him.
"This is just an astonishing picture," said the accompanying breathless message. "This was from a camera found in the wreckage of the WTC, developed by the FBI for evidence and released on the net today... The guy still has no name and is missing." After days of having their senses numbed by a flood of emotionally charged photographs, many people were momentarily tempted to believe that this was just another image of an innocent seconds away from death. However, even the most computer illiterate of us could soon work out that the picture was a fake, the plane having been added to an older image.
The evidence was overwhelming: why was he wearing a thick coat and hat on what was a glorious early September New York morning? How could he have been on the twin towers' observatory deck at the time of the first attack (8.45am) when its opening hours were 9.30am to 9.30pm? Why was the plane coming in from the wrong direction over Manhattan?
Soon it was the turn of the obsessives: how come the plane in the picture was a Boeing 757, not a 767, as was American Airlines flight 11? Why were the angles of the shadows wrong for that time of day (always the first line of inquiry for any true sceptic)? Why was the date at the bottom of the photograph in a different font to the one normally used on date-stamping cameras? The debate became so fierce in the following days and weeks that dedicated websites soon sprang up. People even began to give the mysterious man nicknames, such as Tourist Guy, Tourist of Death and Waldo.
Then began the digital manipulation of the digitally manipulated original: dozens of pictures appeared in which the tourist was placed at other historic events. Hey, there's Tourist Guy behind Churchill at the Yalta conference. And there he is in the limo with JFK in Dallas. Is that really him in front of the burning Hindenburg zeppelin? (If Richard Dawkins is looking for a study aid to explain mimetics - his theory of cultural replicators - this would be ideal.) Another internet phenomenon had been born. But one fact remained stubbornly elusive: who was this man?
Rumours abounded as the search turned global. Chatroom talk was of students in California. Or was it perhaps a gloating Osama bin Laden sympathiser? Then, earlier this month, as the "official" Tourist Guy website reported that it was now receiving 60,000 visitors a week, came the first firm lead. A man in Brazil was saying he was Tourist Guy. José Roberto Penteado, a 41-year-old businessman from the city of Campinas in the state of Sao Paulo, claimed responsibility and, crucially, said he had the photographs to prove it.
He appeared on Brazilian chatshows, gave interviews to local newspapers, handed out autographs to fans and was even, allegedly, contacted by Volkswagen, who wanted him to feature in a TV commercial. ("The first thing I'm going to do when I get the money from Volkswagen is to make a big donation for children in need here," he was reported as saying.) But when he finally posted the photographs of himself on the internet, most agreed that the required true likeness to Tourist Guy just wasn't apparent. His jawline was all wrong and he lacked Tourist Guy's prominent Adam's apple. The misinformation superhighway had claimed yet more gullible victims.
All then went quiet. The spoof images still kept appearing - Tourist Guy aboard the bombed USS Cole, Tourist Guy driving the hijacked bus in the action film Speed - but the leads dried up.
However, at the same time in Hungary, a set of friends had begun arguing over whether to expose the real Tourist Guy after hearing of the Brazilian impostor who now stood to profit from his false claims. For two months they had known the identity of the infamous tourist on top of the twin towers, but had feared the repercussions for him if they went public.
Finally, the group decided that he deserved his 15 megabytes of fame and passed on comprehensive proof - the accompanying set of photos from the same tourist trip to New York - to the Hungarian news website Index.hu last week. Even though Tourist Guy only tentatively agreed to speak to the website via an email interview, his photographs are a compelling match to the original. The "truth" was finally out.
It can now be revealed that Tourist Guy is, according to Index.hu, Peter Guzli, a 25-year-old from Budapest. He claims that after watching the collapse of the twin towers his mind was inevitably drawn, like so many of us, to his own trip up to the observation deck of the north tower during a trip to New York in November 1997. Upon flicking through his snapshots, he found the now notorious photograph of himself posing for the camera with the long, thin island of Manhattan stretching back behind him. It is an image that must have been captured by millions of tourists before and since; when he used his computer to add an image of a plane coming towards him and emailed it to some friends as a "joke", he evidently didn't count on it becoming the catalyst for an truly global phenomenon.
So does he now regret what was an admittedly misguided, but initially private, prank between friends? "I intended this joke for my friends only, not for people who did not know me. I know who the person is [who betrayed him and sent the image on to a wider audience]. I've had a discussion with them, and there's no hard feelings."
Admirably forgiving, perhaps, but what did he think when he watched from Budapest as, albeit briefly, his face became one of the most famous in the world? "I did not have sleepless nights... but I certainly didn't want people to point their fingers at me on the street." Hence Guzli laid low, despite a clamour for his identity to be revealed, in the hope that the unwanted attention would melt away, but even today he doesn't feel any guilt for what he helped to create: "I don't think this thing has to do with empathy or the lack of it. The people I intended it for all said they had a great laugh. That's all."
When asked whether he is now tempted to cash in on his notoriety, he offers a tentative, "Maybe," before adding, "VW, by the way, has cancelled its offer for an advertisement." He is doubtful that his life will ever be the same now that his identity has been exposed. "I'm not sure if there's a way back."