CHICAGO (CBS) — A detective with the Chicago Police Department is suing the city of Chicago for allegedly violating the Illinois Whistleblower act by retaliating against her for reporting the possible misconduct of two officers.

Beth Svec, a member of the police department for more than 18 years, was chosen in July 2015 to participate in a pilot program on the South Side in which detectives conducted follow-up investigations on cases involving arrests for unlawful possession of guns, according to the lawsuit filed Thursday in Cook County circuit court. The policy was expanded to the entire city in fall 2015.

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Svec was assigned to work in the Area South police facility at 727 E. 111th St., investigating gun cases in four police districts, the suit says. She was assigned on May 30, 2016, to investigate a gun case involving two officers who arrested two men in the Calumet District.

The officers told Svec in an interview that they were driving down Stewart Street that morning when they saw a man sitting on top of a gun on a barstool on the front porch of a home, the suit says.

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The officers said they approached the man and took him into custody when another man who was on the porch got angry and punched one of them in the head, according to the suit. They said that man was then subdued and also arrested.

The two officers were seeking felony charges of unlawful possession of a weapon and aggravated battery to a police officer for the two men, according to the suit. The version of the story they told was documented in an official police report that both officers wrote and submitted to supervisors.

Svec followed up by interviewing the two men who were arrested, both of whom refuted the officers’ allegations, the suit says. Svec then interviewed eyewitnesses who saw the arrest and recovered video that contradicted the officers’ accounts.

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