HARRISBURG -- Penn State defensive coordinator Ted Roof has resigned to become the defensive coordinator at Georgia Tech.
Under Roof, Penn State's defense allowed just 19.1 points per game in 2012, the second-fewest in the Big Ten.
Penn State coach Bill O'Brien has promoted secondary coach John Butler to defensive coordinator, the school announced.
Roof, a native of Lawrenceville, Ga. and a graduate of Georgia Tech, was Auburn's defensive coordinator and linebackers coach from 2009-11, helping the Tigers capture the 2010 BCS National Championship.
He also worked with O'Brien at Georgia Tech from 1998-2001, serving as defensive coordinator the last three years.