The NFL has exonerated Peyton Manning following a seven-month investigation into alleged anti-doping breaches.
The two-time Super Bowl champion, who retired from American Football in March following an 18-year spell, was implicated in a Al-Jazeera America report.
A former anti-aging clinic intern named Charlie Sly was secretly filmed alleging that numerous professional athletes took performance-enhancing drugs.
Manning - a former Denver Broncos quarterback - was accused of using human growth hormone, but the NFL found no evidence to support the allegations.
The league released a statement which read: "Initiated in January, the investigation was led by the NFL's security and legal teams with support from expert consultants and other professionals. The investigation involved witness interviews, a review of relevant records and other materials, online research, and laboratory analysis and review."
It added that Manning and his wife "were fully cooperative with the investigation and provided both interviews and access to all records sought by the investigators."
Green Bay Packers linebackers Clay Matthews and Julius Peppers, free agent Mike Neal and Pittsburgh Steelers linebacker James Harrison were also named in the report and remain under investigation.
