MINNEAPOLIS (AP) — Minneapolis police say they'll no longer use undercover officers to investigate suspected prostitution at massage parlors after three cases were thrown out because of officer conduct.

According to court documents, an officer in each case had sexual contact with suspects. Two cases were thrown out by judges, while the Minneapolis city attorney tossed out a third.

Police Chief Janee Harteau said in a prepared statement Thursday that the department is reviewing the cases, and said it would no longer use undercover operations.

Minneapolis police union head Lt. Bob Kroll defended the officers, saying they were operating within the law and department policy. He told the Star Tribune that the only way to have successful undercover investigations is "if you actually portray the role of a crook."

The three male officers involved aren't under internal investigation.

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