As Alex Gibney spent weeks analyzing footage of Lance Armstrong's bold denials about doping and his eventual admission to years of lies, the Oscar-winning director realized he was dealing with a master of deception.

That web of false stories is unravelled in Gibney's aptly titled documentary "The Armstrong Lie," as the director explores just how far the now-discredited athlete went to maintain the powerful persona he had created, not only as a sports star, but also as a symbol of hope.

"His lie was so big ... It was so appealing, that I think some part of Lance was saying 'look I'm just giving people what they want,"' Gibney said in an interview at September's Toronto International Film Festival.

"You have to admit that he did have extraordinary will. But the fairy tale part of the story -- that's over."

As he put his piece together, Gibney realized that even after Armstrong's admission to thousands of falsehoods, the athlete who beat cancer and went on to become a champion was still trying to spin his own story.

"He's trying very hard to prove to everyone he should still be considered to be a great athlete. That's a part of the story which can be convincing, but that's not the most important part of the story," said Gibney.

"The bigger story is that it was a grievous breach of trust. He took people who had enormous amount of hope -- his story became hope to cancer survivors all over the world -- and he made them complicit in his lie. That and the fact that he attacked people for trying to tell the truth, those two things are really much more damaging to his story and to his myth than doping."

Gibney's documentary originally started out as a piece called "The Road Back" as he followed Armstrong while the seven-time Tour De France winner plotted his return from retirement in 2009. That project was shelved as Armstrong faced a storm of doping allegations, increasingly hard-to-ignore evidence and a criminal investigation in the U.S.

When Armstrong eventually went on television to admit to years of doping, Gibney decided to push on with his project, juxtaposing past denials from the athlete with his later admissions of guilt.

The process got personal as Gibney grappled with the fact that Armstrong had deceived him in earlier interviews, but that feeling of betrayal fuelled the director's search for answers.

"He and I would have conversations and they had to be pretty honest conversations because they had to reckon with the fact that he had lied to me before," he explained. "He would rationalize his behaviour and I would have to challenge those rationalizations."

Armstrong has been banned from cycling for life and had his Tour De France titles stripped away after telling Oprah Winfrey in a January interview that he used performance-enhancing drugs to win the gruelling race.

While Gibney's documentary captures Armstrong on camera immediately after his appearance on Winfrey's show and then interviews him at a later date, it also gives audiences a glimpse into the intense pressures of the professional cycling world, where many athletes appeared to use a combination of tactics to get ahead.

Framing Armstrong's story in that context was important to Gibney.

"There are many shades of grey, and I think when you start to talk about doping you just can't talk about it out of that context," he said. "There's no doubt that Lance was doping at a time when a lot of the other high profile riders were also doping. But at the same time, as somebody says in the film, it doesn't mean that wasn't against the rules."

Ultimately, like many of Armstrong's fans, Gibney couldn't help but be drawn to the story of the man who had come to represent human resilience against the odds, and how that near-mythic tale had been shattered.

"Sports stand for something for us, it's a way of making complicated things simple. Somebody wins and somebody loses, but even that turns out to be not so simple," he said, adding that ultimately Armstrong's story seems to be about morality.

"We're all interested in that -- what's right and what's wrong. That's what I think is ultimately going to resonate with people."