Chicago attorney William J. Costello

William J. Costello


Phone:   630-434-0400 Ext. 121

Direct Line:   (630) 668-4217

Fax:   (630) 434-0444

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After receiving a B.A. in Criminal Justice from the University of Dayton in 2002, William J. Costello graduated from the University of Dayton School of Law in 2007. While in law school, he was a law clerk for Judge Mary Kate Huffman and Judge Patrick McGann when he drafted numerous summary judgment opinions for the Court. During his final year of law school, Bill was a law clerk for Martin, Folino, Stachler, & Harmon where he drafted complaints, motions supporting and opposing summary judgment, and an appellate brief which resulted in the affirmance of the lower court’s grant of summary judgment.

After becoming a lawyer, Bill was a prosecutor for many years at the DuPage County State’s Attorney’s Office in Wheaton. During his tenure there, he tried more than 170 misdemeanor/felony bench and jury trials to verdict and argued hundreds of motions. Bill was also involved in the investigation and charging of serious felonies ranging from sexual assault, kidnapping, robbery and reckless homicide to first degree murder.


  • University of Dayton School of Law, Dayton, Ohio, 2007
    • J.D.
  • University of Dayton, Dayton, Ohio, 2002
    • B.A., Criminal Justice

Past Employment Positions

  • University of Dayton School of Law, Law Clerk
  • Martin, Folino, Stachler, & Harmon, Law Clerk
  • DuPage County State’s Attorney’s Office, Prosecutor

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Main Office
  1001 Warrenville Road, Suite 500
Lisle, IL 60532



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