Siller, a Detroit native who started three games at quarterback last fall, is dismissed through the 2009-10 academic year. He could return to Purdue after that time, a team spokesman confirmed.
"It's a disappointing conclusion and, as a football team, we feel for Justin and his family," head coach Danny Hope said in a prepared statement. "Justin made a mistake -- a bad decision -- and deserved to be punished. Our hope was that he would not be punished to the extent he has been. Now it is our responsibility to accept the decision and move forward. Justin is a fine young man, and we wish him nothing but the best."
The 6-4, 220-pound sophomore had participated in Purdue's first four spring practices.
Siller was competing for the starting quarterback spot alongside senior Joey Elliott. He threw for 496 yards and three touchdowns last season after being moved back to quarterback from running back. Following injuries to starter Curtis Painter and Elliott, Siller made his first career start against Michigan and racked up 343 total yards and four touchdowns (3 pass, 1 rush) in a 48-42 victory.
Elliott is now the clear frontrunner for the job, though depth has become a concern with Siller gone. Hope has been pleased with the spring progress of redshirt freshman Caleb TerBush, who moves into the primary backup role.
"The most important thing to me is the development at the quarterback position, not just one particular quarterback," Hope told ESPN.com on Monday. "We'll play as many players as we can, so I'm not really concerned about saying there has to be a certain deadline or due date as long as each and every one of our quarterbacks are improving and can get themselves in position to help us win."
Adam Rittenberg covers Big Ten football for ESPN.com. He can be reached at email@example.com.