College commencement speakers: Who was chosen, and why?

From the Chicago Tribune:

Come graduation season, choosing the right commencement speaker is crucial — just ask Notre Dame.

University presidents scramble all year planning who’s going to deliver an address that symbolizes not only the school’s status but the students’ character as well. Here’s who’s speaking this year at some local colleges and why….

Knox College

Speaker: Patrick Fitzgerald, U.S. attorney whose investigation led to the arrest of former Illinois Gov. Rod Blagojevich

Why: At Knox, the students choose their commencement speakers based on public service.

Alternate reason:
What better way to get immunity from any potential future prosecution?