Transcript for Better, Faster, Suspended? Olympic Athletes and Doping
And now from today's Olympic results my co anchor Bill Weir joins us from London bill. Cynthia I tell you one way or another one part of team USA figures out a way to thrill us on a daily basis. Here in London tonight it was the women's soccer team -- extra minutes. BR North American neighbors Canada to advance to the gold medal game against Japan. But disappointment for Debbie Douglass finishing last in the uneven bar she has one more shot at precious metal tomorrow on the balance beam. Meanwhile a lot of excitement and a little bit of the suspicion. Bubbles up every time somebody -- say. World beating number on the scoreboard in that stadium across the way. Despite reinvigorated testing efforts. Every games is haunted by doping scandals past this -- is no exception so we -- How clean are the athletes of London -- twelve and the answer. Depends on who you ask. In these soft London after -- Hussein -- hundred meter win is being called the greatest race ever. But those with long memories and -- -- call another sprint received equally ecstatic billing in the days after. When Ben Johnson. Beat Carl Lewis at the NBA games in -- The world swooned over the Canadian superhuman speed. -- until three days later he tested positive for steroids. And sent home and a cloud of scandal. And -- 24 years later that final is considered the dirty -- race in history. Because as journalist Richard Moore points out in his new book. Four other screeners in that race went on -- suffered doping scandals of their own so it wasn't just Ben Johnson. -- and that's the point I think you know that claim he was. He was made the scapegoat and I wanted to draw attention -- the he probably wasn't the only one the man ultimately won that -- race is Carl Lewis and after -- stunning performance in Beijing. He was the highest profile name to raise suspicion. Saying quote if you don't question -- times and sport that has the reputation has right now. You're a fool period but the doping control officer at the Salt Lake City games disagrees. You -- ball is a fantastic runner. What a bunch of athletes start to complain. They're out there might be reason -- there might be jealous began -- innocent until proven guilty. -- American officials question the blazing times of young. The Chinese were outraged and -- similar innuendo what Michael Phelps and Katie -- Jackie. Like bull they are athletes with clean records competing in sports with dirty pasts so what has changed in -- plus year. The one thing -- -- changes we've got a World Anti Doping Agency and which is that the independent body that the sport the sport always needed. And in those days you -- sports policing themselves. In addition to this just say no campaign in the IOC's has a record 5500 athletes will be tested these games but so far. They village -- five obscure names. An Albanian weight lifter and news Becky gymnast and an American who tested positive for marijuana after finishing seventh and judo. And in the going to be reading shoulder could get the most who they want -- they didn't as the months very very precisely this device here. But I do get -- -- look -- thinks he sees. Chris Cooper as a biochemistry professor at the University of Essex author of run swim -- -- He believes less than 10% of olympians are doping the hard part -- figure out which ones. When you watch the games. And you see an amazing. What goes through your mind any suspicion. I'm doing -- cartel and we've done it then it every -- we'll listen -- to -- and I know people like them to and they say. That you must be it was quite so I think I think I suspect faces. We should know how buttons. And is there more scrutiny for the better athletes people in this Hussein -- Class is it harder for him but don't that I would be first of an obscure discus throw I would say it's it's a beautiful home victory -- -- Happens of Batavia. We have a very expensive drug testing program here in London. For these Olympic Games I wonder how effective -- -- its money. Well spent and yes like airport security checking everybody how effective really is as a way of combating terrorism. As for bold he's long maintained his skills come from his parents. His Twitter bio boasting the most naturally gifted athlete the world has ever seen. Which makes this picture even more impressive bolts we get a shot himself with these Swedish handball team at 3:45. AM. And he still has two races left to -- He is super human in many ways.
This transcript has been automatically generated and may not be 100% accurate.