Foreign and Greek media have raised United States intelligence agencies as the main suspects. AFP reported that one Greek official stated on background that the likely initial penetration occurred during the run-up to the 2004 Athens Olympics, stating: "it is evident that the wiretaps were organized by foreign intelligence agencies, for security reasons related to the 2004 Olympic Games." The leader of the PASOK socialist opposition George Papandreou said that the Greek government itself had pointed towards the US as responsible for the wiretaps by giving up the zone of listening range, in which the US embassy was included. In 2015, after an investigation lasting 10 years, Greek investigators have found conclusive evidence linking the wiretapping to the US Embassy in Athens. As a result of the investigation, Greek authorities have issued an arrest warrant for a certain William George Basil, a NSA operative from a Greek immigrant background.