Ex-prosecutor sues Kane County, state’s attorney; claims firing was whistleblower retaliation

A former Kane County prosecutor is suing State’s Attorney Jamie Mosser and the county, alleging he was fired after exposing what the suit claimed was a common and longstanding practice of “backdating” criminal complaint filings.

The whistleblower complaint, filed March 16 by former Kane County prosecutor Eric Walliser, asserts that he was trained by more senior prosecutors “to leave petitions or motions on the clerk’s desk ... and the deputy clerk would process and file-stamp the document on the following business day using the prior business day’s date.”

Walliser believed backdating files violated the law or posed a danger to public safety and the fairness and integrity of court proceedings, according to the lawsuit.

“The complaint alleges that this backdating practice could have affected filing deadlines, driver’s license suspensions and revocations, whether cases remained legally valid, and whether people could end up in jail,” Walliser’s attorney Matthew Custardo stated in a news release.

He said the case is about more than just a prosecutor being fired.

“It is about an institutional backdating practice that Mr. Walliser reported internally, and the State’s Attorney’s decision to make him the fall guy instead of confronting the broader problem,” Custardo added. “When a prosecutor is fired days after disclosing a systemic court-record practice, that raises serious questions about retaliation, accountability, and public trust.”

In an email, Mosser said: “While I cannot comment on a pending lawsuit, my office intends to vigorously defend Kane County in this litigation and we look forward to presenting all of the facts in the proper legal forum.”

Walliser’s lawsuit contends that multiple prosecutors and deputy clerks participated in or permitted the backdating practice, that supervisors were aware of it, and that the practice affected legally significant filing dates and downstream criminal consequences.

Walliser began work as a prosecutor on Aug. 30, 2022, and was counseled by more senior prosecutors that the backdating of file-stamp dates was normal, the lawsuit stated.

“Plaintiff was told this was normal, accepted, and had been occurring for years in the branch courts, and based on his conversations with deputy clerks and other courthouse personnel, Plaintiff understood that similar file-stamping and backdating practices also occurred in the main courthouse and were not confined to the branch court system alone,” according to the complaint.

Backdating became normalized because it avoided overtime and did not require branch courts to be staffed to ensure same-day physical file processing, the lawsuit alleged.

The suit states that on or about Feb. 24, 2025, Walliser realized a court document had not been brought to the clerk on the previous Friday to be stamped, so he presented it to the clerk on Monday to be file-stamped with the prior business day.

Walliser was placed on paid administrative leave on Feb. 27, 2025, pending an internal investigation, during which he “affirmatively disclosed that a broader, longstanding institutionalized file-stamping and backdating practice existed in Kane County court operations ... (and) that the practice had been taught to him as normal and routine,” according to the complaint.

After Walliser’s disclosure, defendants stopped the backdating file-stamping practice, the lawsuit states.

On March 17, 2025, Walliser was fired, which the “defendants justified ... by characterizing (Walliser’s) conduct as ‘fraud on the court,’” while minimizing or ignoring the broader practice, the lawsuit alleged.

Because her office was under scrutiny for its handling of a DUI case that later resulted in a fatal crash, Mosser had an incentive to “characterize Plaintiff as a lone bad actor after he disclosed an entrenched file-stamping practice,” the lawsuit alleged.

Walliser seeks back pay, lost benefits, reinstatement or front pay, compensatory and statutory damages, attorney’s fees, correction of his personnel records and other relief the court determines, the lawsuit stated.