The Denver Broncos have never lacked for confidence in Von Miller on the field and that confidence has not wavered now that the star linebacker is participating in training camp under the threat of a four-game suspension for violating the league's drug policy.

Miller has filed an appeal with the NFL to get the suspension lifted and though such wins are rare those close to Miller believe he will eventually be cleared. A person with knowledge of Miller's situation told USA TODAY Sports that the suspension was not the result of a failed drug test.

"He didn't test positive for anything" the person said.

The person spoke on condition of anonymity because drug test results are to remain confidential. The NFL does not announce suspensions until after the appeal process is over.

The person also confirmed a report from The Denver Post that Miller had tested positive for marijuana in 2011 Miller's rookie season a result that landed Miller in the league's drug offender program. That program has several phases and includes random unannounced drug tests.

According to the NFL's drug policy passed by the league and players' union in 2010 players in the second phase of the program also can be suspended for failing to comply with the terms of the policy.

That could include a player missing a drug test or providing a diluted urine sample.