"Lance has not been subpoenaed in this investigation that's going on, nor has he been contacted in any way. ..." he said. "Of course, as Lance has said, he would -- he's going to cooperate with any legitimate, fair investigation. But not participate in a witch hunt. And so far, this has all the markings of a witch hunt."
We asked Landis about his changing version of events.
Nightline: You realize you have serious credibility issues?
Landis: I think that'd be an understatement.
Nightline: You're an admitted liar and cheat.
Landis: What -- what is a person supposed to do when they make the wrong decision? I mean, are you committed to that path for good? Are you -- once you tell a lie, are you committed to tell that lie forever?
Nightline: Well, Lance says you have no credibility.
Landis: You just said I have no credibility.
Lance Armstrong forcefully has denied Landis' claims.
Landis told us he first started using perforance-enhancing drugs when he joined the U.S. Postal Service team, led by Armstrong.
"Lance Armstrong handed me some testosterone patches," Landis said. "It's just a little patch that you put on your skin. It's not like it's a-- I mean, a blood transfusion is a bit more dramatic. It's a large needle. And it's blood. But a patch that delivers testosterone? A trans-dermal patch? Not anything dramatic."
Nightline: Did you see Lance Armstrong receiving transfusions?
Nightline: More than one?
Landis: Yes, multiple times.
Landis says Armstrong -- his former teammate and friend -- transfused his own blood, a banned practice that gives endurance athletes an advantage by increasing their red blood cell count and, therefore, their endurance. Lance Armstrong and his lawyer both have categorically denied that he has ever cheated.
A banned substance called EPO provides a similar effect.
Nightline: Did you see Lance Armstrong using other performance-enhancing drugs?
Landis: At times, yes. At different training camps.
Nightline: Like what?
Landis: Well, there's not a whole lot. Like I said, at that house, there's EPO he can use. And you can use small amounts during the Tour de France if you need to monitor certain parameters that are better tested for, that change because of the blood transfusions.
Nightline: When you saw him using EPO?
Landis: I had, yes. Also received some from him. Rather than go into the entire detail of every single time I've seen it, yes. I saw Lance Armstrong using drugs.
Nightline: I have to say, Floyd, you say it in such a matter-of-fact way. And yet, this is a man, Lance Armstrong, who has denied up and down for a decade that he's on anything but his butt ... Anything but just hard work.
Landis: I denied it as well.
Nightline: You're saying Lance Armstrong is a liar.
Landis: Yes, I suppose, if that's the question, yes.