NILES, Ill. (CBS) — A former Niles police commander said he blew this whistle on police misconduct and it ended up costing him his career, but the Niles police chief claims the commander caused his own demise.

Now, former Niles police Cmdr. Nick Beyer is taking the department to court. This is the result of a story that CBS 2 Political Investigator Dana Kozlov reported back in April, since which Beyer was demoted and ultimately resigned after the department turned the tables on him.

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Beyer spoke with Kozlov on Thursday about why he decided to file that whistleblower lawsuit and keep fighting.

A 911 call back on Feb. 28 first triggered misconduct alarms with former Cmdr. Beyer. Officers showed up to a local McDonald’s to find a part-time Niles village employee passed out in the front seat of his car at the drive-through.

Police body cam video obtained by the CBS 2 Investigators shows the man clearly slumped in his car. But instead of waiting for a report, calling an ambulance, or making an arrest, Beyer said Niles officers drove the man home – 40 miles away.

“The fact that there was never a report taken on that to begin with is a smoking gun. The fact that the officer manually shut off the body cameras is a smoking gun,” Beyer said.

Beyer said he learned about the incident from a fellow officer. He later brought his concerns to higher-ups, but refused to give supervisors the officer’s name.

That was when the 22-year department veteran was put on leave for insubordination. He was demoted two months later, and then resigned after the department suddenly dug up dozens of misconduct concerns about him.

“I think that they huddled in their war room for weeks on end with attorneys to figure out whatever they could do to fire back at me,” Beyer said.

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In July, Niles police Chief Luis Tigera said, “We conducted a thorough, exhaustive, and unbiased investigation,” as he cleared the officers involved in the February call.

“The evidence revealed no merit to the assertion that there was an effort by the NPD officers to cover the incident,” Tigera said.

But Beyer is not backing away from his misconduct and cover-up claims. He questions the integrity of the village’s investigations, saying investigators never even talked to him.

All his concerns are now laid out in a federal whistleblower lawsuit – charging, among other things, retaliation.

“I am continuing the fight, just in an objective forum,” Beyer said.

On Thursday afternoon, a Niles village spokesperson said the village is declining to comment on the lawsuit at this time.

Meanwhile, another investigation is also under way into the matter. In April, Beyer filed a complaint with the Cook County State’s Attorney’s Law Enforcement Accountability Unit, and a spokesperson there said it is still being reviewed.

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Beyer in the meantime is challenging Niles to release all the police body cam video from that night to the public.