Dumes has been a key part in the Hoosiers' progression this season by becoming more deliberate with his shots and making a better effort to find open teammates and his loss will be felt.
But late in Saturday's loss at Michigan State, Dumes was ejected after drawing a flagrant foul when he threw an elbow at Spartans center Tom Herzog. He was ejected with about 2 minutes left in the game.
"After coming home and having the opportunity to review the game film, I believe that discipline is necessary and deserved in this matter," Crean said in a statement released by the athletic department. "A line was crossed that was unacceptable."
Crean said he hoped Dumes would learn a lesson, and the Big Ten issued a statement in support of Crean's action.
Dumes, in his first season at Indiana, acknowledged he had made a mistake.
"I truly regret my actions and I will learn from this situation," Dumes said. "I apologize to everyone involved for doing something that is uncharacteristic of how I play the game."
It has been a frustrating season at Indiana.
After the NCAA ruled in November on former coach Kelvin Sampson's phone-call scandal, the Hoosiers went on a school-record-tying 11-game losing streak before finally beating Iowa on Wednesday.
Indiana is 6-16 and 1-9 in Big Ten play, its worst season in decades.
Yet over the past several weeks, the Hoosiers nearly ended that long losing streak against Northwestern and Minnesota before finally beating Iowa.
Dumes' progression played a significant part in that improvement.
But losing Dumes, who is averaging 13.8 points per game, is an even bigger blow to a program that was gutted after last season. Crean had only two returning players on this season's roster and still has only eight scholarship players, including Dumes.
That's left Indiana in dire need of depth, something that will become an even bigger problem without the junior guard who played high school ball at Decatur Central near Indianapolis. Dumes has also played at Eastern Michigan and Vincennes University in southwestern Indiana during his college career.
But Crean felt he had no choice in this matter.
"Devan is one of ours and, like with all of our players, we want them to learn and understand what it takes to be successful," Crean said.
The Big Ten agreed.
"The behavior of Devan Dumes during the Michigan State game is unacceptable," conference commissioner Jim Delany said. "Dumes' actions have no place in the sport of basketball or the Big Ten Conference, and we support his indefinite suspension."
It's the second time in less than two weeks a Big Ten player has been suspended for a flagrant foul. Michigan's Zack Novak drew a one-game suspension Jan. 30 after elbowing Ohio State's P.J. Hill late in a 72-54 loss.
Crean gave no indication how long Dumes may be out.