Los Angeles - Federal prosecutors on Friday dropped an investigation centered on whether seven-time Tour De France champion Lance Armstrong and his teammates cheated the sponsor of their bike racing team with a secret doping program.The decision means that Armstrong, a cancer survivor and one of his sport's greatest champions who has always vehemently denied using performance-enhancing drugs, will not face charges following the two-year-long probe."I am gratified to learn that the US Attorney's Office is closing its investigation. It is the right decision and I commend them for reaching it," Armstrong, 40, said in a statement released through his spokesman."I look forward to continuing my life as a father, a competitor, and an advocate in the fight against cancer without this distraction," he said.