Denver Broncos Pro Bowl linebacker Von Miller could be suspended four games by the NFL, ESPN's Adam Schefter reported Monday.
It is not clear which policy Miller is accused of violating because the suspension is under appeal.
However, there are indications that the suspension is the result of substance abuse.
Miller said in his Twtter account that he did nothing wrong, writing, "Seeing reports abt 4 game susp," Miller wrote. "I know I did nothing wrong. I'm sure this'll be resolved fairly. Disapp. Broncos have 2 open camp like this."
NFLPA spokesman George Atallah said on Twitter that Miller's potential suspension did not result from steroid use, writing, "I can also confirm that Von's case does not involve the Steroids and Related Substances Policy."
That leaves substance abuse, according to a conclusion reached by ProFootballTalk.com.
The Denver Post reported that Miller tested positive in 2011 for amphetamines, which is prohibited under the steroids policy, and for marijuana, which is prohibited under the substance-abuse policy. Miller apparently avoided a suspension for the positive amphetamine test.
Miller has gone to the Pro Bowl in each of his first two seasons in the NFL. He had 11.5 sacks in 2011 and was named NFL Defensive Rookie of the Year. Last season, he had 18.5 sacks and was named a first-team All-Pro. He was the No. 3 overall pick of the 2011 draft.
Miller is scheduled to earn $2.284 million in base salary this season. A four-game suspension would cost Miller $537,441 from his salary. He was also the recipient of a $13.773 million signing bonus. The team will likely look to recoup more than $200,000 of that.
Last week, the Broncos suspended personnel executives Tom Heckert and Matt Russell stemming from their recent drunk-driving-related arrests.