US prosecutors have dropped their investigation into seven-time Tour de France champion Lance Armstrong and other cyclists without bringing criminal charges.
The probe has reportedly included a grand jury sitting in Los Angeles hearing testimony from former Armstrong teammates and associates.
Although such grand jury proceedings are supposed to remain secret, the investigation has been widely reported on, prompting the prosecutors office to take the step of announcing it had ended.
Armstrong, who won the Tour de France from 1999-2005, has vehemently denied using performance-enhancing drugs during his cycling career.
However, he became the subject of the probe by federal investigators who were trying to determine if the US Postal cycling team owed much of their success to a systematic doping programme.
The investigation was sparked in part by confessed dope cheat Floyd Landis, who claimed Armstrong schooled him in doping techniques when they were teammates.
Landis was stripped of his 2006 Tour de France title but didn't admit doping until 2010.