Conte, founder of the California-based Bay Area Laboratory Co-Operative, which is facing federal charges for distributing steroids and other illegal performance-enhancing drugs to athletes, says he supplied Jones with a variety of illegal drugs from August 2000 through September 2001. He claims to have supplied her with a substance called "the clear," EPO, human growth hormone, and insulin. (The clear is thought to be the anabolic steroid tetrahydrogestrinone, or THG. EPO, an acronym for erythropoietin, is a red blood cell-boosting hormone experts say can increase endurance by 10 percent to 15 percent.)
"After I instructed her how to do it and dialed it up, she did the injection with me sitting right there next to her, right in front of me," Conte says. "Marion didn't like to inject in the stomach area. ... She would do it in her quad. The front part of her leg," he tells "20/20."
Jones, described as the fastest woman on Earth, won five Olympic medals at the 2000 Olympic Games in Sydney, Australia. Rumors of performance-enhancing drug use have dogged her, but she has never failed a drug test and maintains she has never used illegal drugs.
Conte says there simply aren't accurate drug tests to detect the substances he claims Jones used. "As I told you earlier ... it's like taking candy from a baby," Conte tells "20/20."
Jones declined to be interviewed for this story. In a written statement to ABC, her lawyers insisted Jones "has never, ever used performance-enhancing drugs" and that she "passed a lie detector examination." They also said, "Victor Conte is simply not credible."
In a statement released today, Jones said, "Victor Conte's allegations about me are not true, and the truth will come out in the appropriate forum. I have instructed my lawyers to vigorously explore a defamation lawsuit against Victor Conte."
"I have no bone to pick with Marion," Conte tells "20/20's" Bashir. "I'm here today because I believe that the world needs to hear the truth, the whole truth and nothing but the truth, so that we can really attempt collectively to try to genuinely create a level playing field for the athletes of the future.
"It's almost like what I'm here to tell you right now is that not only is there no Santa Claus, but there's no Easter Bunny or Tooth Fairy either, in the world of sport ... I mean the whole history of the Olympic Games is just full of corruption, cover-up, performance-enhancing drug use -- it's not what the world thinks it is," Conte says.
Conte asserts the use of performance-enhancing drugs is essential to level the playing field. "It's not cheating if everybody is doing it. And if you've got the knowledge that that's what everyone is doing, and those are the real rules of the game, then you're not cheating," he tells Bashir in the "20/20" interview.
Also on "20/20," Kelli White, the track and field star who tested positive for steroids, talks for the first time about what happened after she approached Conte.
"He made me believe that if I followed a certain protocol of supplements and different drugs that I could become number one in the world," she tells "20/20."
She says she saw a difference within a week or two of beginning the Conte-prescribed regimen. "I saw myself on TV and I was kind of unhappy about that. I was huge, very big, very muscular -- none of my clothes fit. And so it was, it was difficult. I knew that looking that way would get a lot of whispers," she said.