Defending champion race walker Alex Schwazer tested positive for a banned substance and has been pulled from the London Games. The Italian Olympic Committee was informed Monday that the World Anti-Doping Agency found Schwazer to have been taking the banned blood booster EPO. "My career is over. I made a mistake. I wanted to be stronger for this Olympics, I was wrong," Schwazer said in a statement to the ANSA news agency. The 28-year-old athlete took gold at the 2008 Beijing Games, winning the 50K race walk in the Olympic record time of 3 hours, 37 minutes, 9 seconds.