Athletics is facing a new crisis after fresh allegations of suspected doping emerged following a leak of test data. The Sunday Times and German broadcaster ARD/WRD have obtained access to the results of 12,000 blood tests from 5,000 athletes. The evidence reveals the extraordinary extent of cheating by athletes at the world's biggest events. The investigation used two of the world's foremost anti-doping experts, scientists Robin Parisotto and Michael Ashenden, to review the data. The files belong to world governing body the International Association of Athletics Federations, but have been leaked by a whistleblower.