Robbinsdale Police Chief Steven D. Smith kept his prostitution arrest secret from other city officials for more than a month before suddenly turning in his car and quitting Saturday, just days before his expected court appearance.

“It is disappointing it took an entire month,” said Regan Murphy, the Robbinsdale mayor. “That is on Steve Smith, why he chose to withhold that information from his employer.”

Murphy said he and other council members are “frustrated and a bit angered” by the surprise revelation that Smith was one of 10 people arrested and cited for prostitution in a Feb. 20 sting operation at a private residence in Coon Rapids. The mayor said he expected Smith would be arraigned Monday.

Although he praised Smith’s work since becoming chief in 2008, Murphy said the former chief had “betrayed the trust of the residents which is very discouraging.”

Murphy said Smith verbally resigned Saturday after contacting the city manager, who gave other city officials the first word on the incident. Capt. Jim Franzen was quickly named acting chief. He could not be reached for comment Sunday.

Murphy said he hopes Robbinsdale residents judge the police department based on “personal interactions with the officers, rather than on the off-duty actions of one individual in another city.”

Coon Rapids City Manager Steve Gatlin said he also learned about Smith’s citation Saturday morning from his police chief. He then notified Coon Rapids council members. Gatlin said he didn’t know how or when Chief Brad Wise learned about Smith’s citation, or if anyone from Coon Rapids called Robbinsdale officials.

Wise, a police captain and City Attorney David Brodie, who also was aware of the case, didn’t return calls Sunday. The city attorney prosecutes misdemeanor cases such as prostitution between consenting adults.

A police release Saturday said Smith, 45, was arrested, cited and booked for hiring or engaging in prostitution and released from the Anoka County Sheriff’s Office on Feb. 20. The release noted that Smith provided no information about being a law officer.

Coon Rapids Mayor Tim Howe said he also heard Saturday about the Robbinsdale chief’s month-old arrest. “Our department must be doing their job,” Howe said. “Our city manager called me Saturday morning, and said we’d be hearing about it on the news. That’s the first I knew about it.”

Generally speaking, prostitution between consenting adults, with no prior offenses, is a misdemeanor offense in Minnesota, said Paul Young, lead prosecutor for the Anoka County Attorney’s office, which handles felony sex charges. Young said he’d heard nothing about the case other than news reports.

Smith “is not getting something special,” by receiving a misdemeanor citation, Young said. “He was treated the same as anybody else caught up in the same kind of thing: a guy caught in a sting.”

Howe also said he didn’t think police had tried to protect Smith because they could have let him go without a citation.