Federal prosecutors have subpoenaed documents from an arbitration case concerning whether Lance Armstrong used banned performance-enhancing drugs. The sought documents include depositions that Armstrong’s teammates gave when a promotions company was trying to prove that the cyclist was doping. Armstrong has denied all doping charges, which have popped up periodically over his long career. Though doping is generally not illegal in the U.S., prosecutors could say Armstrong defrauded investors if he accepted sponsorships based on an agreement not to use the banned substances. The investigation began this spring after cyclist Floyd Landis claimed publicly that doping was widespread among cyclists, including his former teammate Armstrong, whom Landis says he saw use drugs. Others have testified that Armstrong admitted to using drugs. The seven-time Tour de France winner says they’re all lying.