(CNN) -- Oscar Pistorius' family disputed the prosecution's contention that a banned substance was found in the athlete's house. "Oscar, was not using any drugs listed on the World Anti-Doping Agency banned substances, usage of which would ban him from competing in athletics competitions," the family said in a statement Thursday. "The IAAF will have records of every single drugs test that was undertaken in and out of competitions. He has been tested on a number of occasions during the last couple of years and he has never failed a drug test to date."