(CNN) -- As police tell it, he called himself "Scott" and showed up with $150 at the ready.
He was drawn to a house on the outskirts of Minneapolis by an online ad that promised a "no limit experience" with the catchy tagline, "Sick of winter? Come see how Sommer feels."
Within minutes, he'd been cuffed, read his rights and cited for engaging in prostitution by undercover detectives in Coon Rapids, Minnesota. He was one of nearly a dozen men arrested as part of a sting operation, and exercised his right to remain silent, according to police reports.
"Scott" turned out to be Steven Smith, a fellow cop -- in fact, the police chief of the Minneapolis suburb of Robbinsdale. Officers learned his real name the night of his arrest on February 20, but only discovered his law enforcement role when preparing documents for his lawyer last week, Coon Rapids Police Chief Brad Wise said.
"It was at that time that a staff member recognized Smith's photo as that of the Robbinsdale police chief," Wise said in a written statement.
Smith was released after booking on the misdemeanor charge and has since resigned his post, CNN affiliate WCCO reported. His lawyer, Paul Sarratori, declined comment Tuesday.
Wise said nothing Smith carried at the time of his arrest identified him as a law enforcement officer.
"Mr. Smith did not ask for special treatment upon his arrest, nor did he receive treatment different from any other person arrested in this operation," Wise said. Coon Rapids police "followed all protocol and procedure" during the arrest, he added.
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