Travis Tygart says he spent years probing the biggest doping scheme in sports history, and received death threats, including one chilling warning that he would get a bullet to his head.
In an interview on 60 Minutes Sports, Tygart, the head of the US Anti-Doping Agency (Usada), described the sophistication of the Lance Armstrong doping scandal, which included the use of untraceable mobile phones, makeup to hide needle marks and an offer of a US$250,000 donation from one of Armstrong's representatives to Usada in 2004.
An investigation into the scheme resulted in the disgraced Armstrong being stripped of his seven Tour de France titles and banned from the sport of cycling for life.
Tygart said Armstrong had been tipped off by the director of the Swiss drug testing laboratory, Martial Saugy, about how to beat the erythropoietin (EPO) test in 2002 after one of Armstrong's samples from the 2001 Tour of Switzerland was described as "suspicious".
"[Saugy] sat down next to me and said, 'Travis, in fact, there were samples from Lance Armstrong that indicated EPO use'," Tygart said. "As far as we are aware, [it is] totally inappropriate to bring in an athlete who had a suspicious test and explain to them how the test works."
Tygart said six of Armstrong's samples taken during his first Tour de France win in 1999 were originally reported as negative but they were re-tested in 2005. "All six were flaming positive," he said.
Tygart said much of the information used by the investigation was obtained from the dozen former US Postal team members who were willing to testify against Armstrong, including Dave Zabriskie and George Hincapie.
He described a culture of fear among the cyclists who rode alongside Armstrong which was designed to keep the doping scheme secret and prevent anyone from blowing the whistle on the star athlete.
Hincapie told Tygart of a race in Spain in 2000 in which he texted a warning to Armstrong that he was about to be tested. Armstrong "dropped out of the race to avoid testing", Tygart said.
"Our job is to follow the evidence," Tygart said. "We asked riders to come in and be truthful, nothing more, nothing less. And they were. We were disappointed [Armstrong] didn't come in and be part of the solution. It's one of the lowest days of this investigation, quite honestly."
The interview was conducted before Armstrong, 41, announced he was going on the Oprah Winfrey television network later this month to tell his side of the story. A spokeswoman for Winfrey insisted no question would be off limits and Armstrong would not be paid for the 90-minute interview.
However, British cyclist David Millar, now a member of the athletes' commission for the World Anti-Doping Agency, was sceptical. "My biggest concern is that it will be completely stage-managed, that he will just be 'given the ball', and that it will all be about his emotions rather than concentrating on exactly what he did wrong," said Millar, who himself served a two-year ban after admitting doping in 2004 and then became a vocal campaigner against drugs in sport.