Two men are now competing to replace him. They're Democrat Gregory Whalen and Republican James Mendrick.
WATCH: Hear from Republican candidate James Mendrick
Newsviews: Candidates for DuPage County Sheriff
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Mendrick is a 22 year veteran of the DuPage County Sheriff's department.
He's held a variety of positions within the department and currently serves as the Patrol commander.
Mendrick says he would bring that experience to the job if elected Sheriff.
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Democrat Gregory Whalen is currently a Lieutenant with the Glencoe Department of Public Safety which cross trains its staff in all three public safety professions: law enforcement, fire and emergency medical services.
Whalen says if elected, he would have the ability to bring all public safety agencies together during major incidents.