INDIANAPOLIS (AP)The NFL suspended Indianapolis Colts starting defensive tackle Grover Stewart six games without pay Tuesday for violating the league’s policy on performance-enhancers.

While league officials didn’t disclose details about the violation, they did say Stewart could return to Indy’s active roster Dec. 4.

Stewart responded to the announcement on Instagram.

“I want to apologize to the National Football League, the Colts organization, my teammates, our fans, and my family,” he wrote.

“I was surprised and disappointed to learn I had violated the policy. I respect the integrity of the game would never purposefully put myself or the team in this kind of situation. I am responsible for what I put in my body, and I should have taken the proper steps to educate myself. I will learn from this moving forward, and I will take the appropriate measures to ensure this never happens again.”

Stewart has been a key part of Indy’s run defense since reshaping his body after being a 2017 fourth-round draft pick out of Albany State in Georgia. He has steadily increased his weight from 295 pounds to 314, taking on a much leaner look as he teamed with two-time Pro Bowler DeForest Buckner to give Indy (3-3) one of the NFL’s top interior defensive tandems.

This season, Stewart ranks eighth on the team with 20 tackles, two for loss, but Colts coaches have repeatedly said he has been playing at a Pro Bowl level for several seasons.

Without Stewart, the Colts will likely move Taven Bryan into the starting lineup Sunday against Cleveland (3-2). Bryan was Jacksonville’s first-round draft pick in 2018, No. 29 overall, but he signed with Indy as a free agent in March.