Naperville police officer used Flock technology to stalk people, records show

A Naperville police officer used Flock Safety license plate reader technology to track a girlfriend and her ex-fiance, according to documents obtained through a Freedom of Information Act request filed by the Naperville Sun.

Oscar Maldonado, who no longer works for the Naperville Police Department, tracked license plates for non-police-related matters hundreds of times between June 18, 2025, and Sept. 15, 2025, records show. When the department received a citizen complaint about the cameras’ misuse, an investigation was conducted.

Maldonado was placed on administrative leave while an internal investigation was done, and ultimately resigned in May prior to the conclusion of the probe, according to a statement from Naperville Police Chief Jason Arres.

Naperville police contacted the Will County sheriff’s office to conduct an independent criminal investigation, which was later turned over to the Will County state’s attorney’s office. A representative for the prosecutor’s office said they could not confirm or deny an investigation.

Automated license plate readers — increasingly synonymous with Flock, though there are other brands on the market — photograph license plates and other identifiers of passing vehicles. Police officers can use the data obtained for investigations.

However, a growing number of officers in the Chicago area and across the country have been accused of searching those databases for personal reasons. Civil liberties activists say they fear law enforcement agencies could use the cameras to work with immigration officials or to surveil law-abiding citizens.

As allegations mount, police departments and lawmakers are grappling with how to prevent the cameras’ misuse.

“The Naperville Police Department has and will continue to develop strong policies and auditing procedures around these sensitive systems and hold individuals accountable for any misuse,” Arres wrote in the statement. “This is precisely the approach we took in this instance and the standard we are committed to upholding for our community going forward.”

The department updated its internal policy on automated license plate reader usage earlier this month, which now includes a new section on the auditing process. Naperville police also reported both Maldonado’s resignation and internal investigation to the Illinois Law Enforcement and Training Standards Board.

According to the documents obtained in the FOIA request, Maldonado began using Flock to track the woman and her ex-fiance shortly after entering into a relationship with the woman.

In his interrogation with the police department, Maldonado said he did not use the technology for a criminal case involving the woman or her ex-fiance but for personal reasons.

When asked why he used Flock to look up the license plates, Maldonado said it was for the safety of the woman he was seeing, himself and his family.

According to both the internal investigation and his attorney, Patty Kalkanis, there were times when Maldonado felt threatened by the ex-fiance, including multiple incidents in which the ex-fiance allegedly tracked Maldonado.

“It wasn’t our client stalking him and our client being the aggressor. We believe that … Mr. Maldonado was only trying to protect himself,” Kalkanis said.

However, the police investigation casts doubt on Maldonado’s explanation, citing instances in which Maldonado used Flock despite there being no clear safety threat.

It also notes that Maldonado never reported his concerns to law enforcement. He also conceded during the interrogation that the information he obtained would have done little to no good in protecting his family.

The police’s internal report found Maldonado violated multiple department regulations, including abusing his authority and breaking the department’s code of ethics.

“(T)here is a preponderance of the evidence that shows Maldonado did commit the crime of official misconduct,” the report states.

Kalkanis disputes the claim that Maldonado’s actions rise to the level of official misconduct due to a lack of state legislative clarity regarding Flock misuse.

“This is Illinois case law, and it is very clear that it is not breaking the law using Flock right now. … There is no law to have been broken. Maybe a violation of an employee manual but I think that’s about as far as it can go,” Kalkanis said.

When asked if Maldonado had any regrets about how he used the Flock system, Kalkanis said the only regret he may have is not informing a supervisor sooner about what was going on.

“He does not have a regret using the tools and the resources he has to protect himself and his family,” she said.

Chicago Tribune staff writers Rebecca Johnson and Lila Hempel-Edgers contributed to this report.

cstein@chicagotribune.com