Von Miller was caught trying to manipulate the NFL's drug-testing system, which led to a six-game suspension that could have been longer.
A person familiar with the case told The Associated Press on Sunday that Denver's All-Pro linebacker tried to avoid a positive test under the league's substance-abuse policy. The person spoke on condition of anonymity because the league has not announced the details of Miller's violation. The manipulation attempt was first reported by ESPN.
Miller's six-game suspension was a compromise among the NFL, the players union and Miller's representatives; the league wanted a longer penalty for the third-year player. When his ban was announced last month, Miller said in a statement, "although my suspension doesn't result from a positive test, there is no excuse for my violations of the rules."
NFL spokesman Greg Aiello and the Broncos declined to comment on Miller's situation.
Miller has also had several other off-field problems. He was cited earlier this month for speeding and driving with a suspended license. At the time, Broncos coach John Fox defended the 2011 Defensive Rookie of the Year, saying the team is helping Miller stay out of trouble any way it can. He stressed that the infractions were nothing more serious than traffic citations.
Miller was arrested in August when he tried to purchase a weapon and a routine background check revealed an outstanding warrant for failing to appear in court on traffic charges from last year. He also was pulled over near his suburban Denver home this month and cited for speeding and driving with a suspended license.
Fox wouldn't say whether the team had designated anyone to make sure Miller takes care of his off-the-field matters in a timely fashion to avoid further embarrassment: "I'm not going to get into all our operations, but it'd be fair to say that we have a lot of great resources here," he said.