THE annals of American history had already reserved a place for William Rodriguez, but he was not content with a mere footnote.

The 43-year-old former New York janitor claims to have been the last man out of the north tower of the World Trade Centre before it imploded on September 11, 2001. Just moments before the tower's final destruction, Rodriguez assisted firemen and rescue crew in saving hundreds of lives. But for the Puerto Rican, the experience also marked the beginning of a life-changing journey - or, in his words, "a quest for the truth".

Rodriguez has become the poster boy for a movement currently sweeping the globe, which claims the official story of what happened on 9/11 - that four US airlines were hijacked by Osama bin Laden's terrorists to attack Western civilisation - is a pack of lies. These activists, who call themselves the 9/11 Truth Campaign, believe the real version of events has been hidden and are convinced that the worst terrorist attack on US soil was perpetrated to justify aggressive US foreign policy in the Middle East.

Partly because he was an eye-witness to the day's events, Rodriguez's testimony plays a key role in giving credence to the allegations of the 9/11 Truth campaign. In the past five years, he has, in effect, turned evangelist for this conspiracy movement, assuming celebrity status among supporters as he travels around the globe lecturing to millions on what he saw and heard on that fateful day.

With the 9/11 Truth Campaign, he insists that both towers were subject to a controlled explosion; and that, moments before the north tower was hit by a plane, he and colleagues heard an explosion underneath their office. This initial explosion was then followed by other bombs. This same version of events is peddled by Loose Change, a 90-minute internet movie made by three American men, which has been watched by an estimated 100 million viewers around the globe. The film, a blitz of statistics, photographs, eyewitness accounts and testimonies, argues that the fire in the towers was not hot enough to melt their steel frames and that they fell too quickly.

Regardless of whether you believe him, Rodriguez's voyage is an extraordinary one. Since 9/11, he has gone from being an establishment figure, taken into the bosom of the Republican party and even groomed for political office, to one who is now considered a maverick in these same quarters. Yet he remains committed to what he calls "a just and truthful cause".

"People say they don't believe in conspiracy theories, and I say neither do I. But I was there that day. I was an eyewitness," he says.

During his talks, he regales predominantly sympathetic audiences with his version of events, as well as tales of the trials he has faced since, including an attempted assassination in Venezuela where he was speaking on behalf of the 9/11 Truth Campaign.

"I turned up half an hour late for work on the morning of 9/11," he says. "Normally I started at 8am, and at 8.30am I would have been having breakfast with colleagues on the 106th floor. But that day I came in at 8.30am because I had phoned in earlier to say I was sick and wasn't coming in at all. My boss, however, asked me to come in because they had no-one to do my job."

Rodriguez, who had worked at the north tower for 20 years, had responsibility for the maintenance of the three stairwells within it: A, B and C. On a typical morning, he would finish breakfast and then begin at the top of the building and work his way down, ensuring everything was clean and in working order. Just before the first plane struck the tower at 8.46am, he was in an office with colleagues on the building's first sub-level when he says they heard "a massive explosion".

"The floor vibrated. We were all thrown upwards, then everyone in the office started screaming. Then we heard another noise, the impact of the plane. It was two different events, separated by a fraction of time. It was a miracle I was there and not in the restaurant," he says.

As only one of five people who held a master key, which opened doors to the stairwells, Rodriguez took it upon himself to begin opening the emergency exits so people could escape. "Nobody wanted to go back into the tower apart from me. I said, We've got to go back in and start saving these people'. So I started doing just that. I let firemen in and together we made our way up the tower's stairwells, opening the emergency exit doors," he says.

Before he did this, Rodriguez recalls, he rescued two people who were stuck in an elevator shaft. Regardless of the danger, he says, he was determined to continue. To this end, he went back into the tower three times after it had been struck and led a further 15 people to safety, one of whom was a paraplegic. He survived the building's collapse by seconds, finding refuge underneath a fire truck. After receiving medical attention for injuries, Rodriguez spent the remainder of the day as a volunteer in the rescue effort, and returned the following morning to help with the clean-up.

FOLLOWING the events of 9/11, Rodriguez was treated as a hero. "Every politician wanted to have their photo taken with me," he says. Among those were Hillary Clinton and President George W Bush. "The Republicans offered me funding to go to politics," he says. "They offered me thousands of dollars of campaign money. They were trying to get the Hispanic vote and saw me as a clear candidate to do that. I was part of the whole party machinery, until I started to ask questions."

Those "questions" primarily concerned how differently the official explanation of events compared with his own and with that of his friends. He is also highly critical of the 9/11 Commission, which started out, he insists, by accepting the official record of events and only included evidence which supported this. "Any contradictory evidence was destroyed or ignored, including testimonies of myself, firemen and others who were there at the time and heard explosions," he claims.

So instead of playing ball with the Republicans, Rodriguez established the Hispanic Victims Group, joined the 9/11 Truth Campaign and worked with the families of victims and injured survivors. He also spent hours testifying - "in secret", he says - in front of the official 9/11 Commission, although his testimony never made it into the report.

"We just wanted to know what happened that day. For me, it's been about the families from the beginning. The official story is simply not true and I'm not the only one who is saying it."

WHEN you consider Rodriguez's testimony, the fundamental question is not whether you believe the official story or not, but whether his version of events is convincing enough. It is beyond doubt that he and his supporters believe his recollection with fervent conviction. However, like so many conspiracy theories, the theory itself is let down by its proponents. During a recent lecture in Glasgow, Rodriguez appealed to the crowd to "examine the evidence". Yet the only evidence put forward in two hours of discussion was his own testimony - and it was clear he was out to convince our hearts as well as our minds. As he described the importance of being a master key holder, he pulled a key from his inside pocket like a magician revealing a vanished coin (incidentally, he used to be a magician before becoming a janitor). He wielded the key triumphantly as if showing us a vital piece of evidence. Of course, for all we knew it could have been the key to his drinks cabinet or front door. Nevertheless, the prop received its intended reaction - gasps of disbelief and wonder. But he had clouded the issue with unnecessary razzmatazz.

Likewise, when explaining how he was the only master key holder to have stayed in the building to aid the evacuation effort, his appeals of "Don't blame them. Don't judge them" seemed crass and insincere. As if we were not going to judge them while we were staring a living, breathing "hero" in the face.

To a seasoned conspiracy buff (and, let's face it, who doesn't love a conspiracy theory?) there was, disappointingly, a vague sense of familiarity about all the unusual behaviour - being late for work for the first time in 20 years; missing testimonies; and mysterious events on the 34th floor (Rodriguez claims he heard the sound of heavy equipment being moved around when he was rescuing workers from the 33rd floor, but this is interesting only because the 34th floor was supposed to be empty).

Yet, frankly, what conspiracy theory doesn't have such elements?