Exposito countered that he had transferred, not demoted, the officers. He said the real reason for his firing was a public spat he had with the mayor over video-gaming machines known as maquinitas. Exposito had seized hundreds of the machines from Miami businesses, claiming they were illegal under state law. Regalado disagreed and championed a measure allowing them under certain conditions.

Exposito said that other city employees have clashed with the mayor and paid a similar price.

“When people do not want to do things that are unethical, immoral or illegal, they are pushed out or they leave on their own,” Exposito said.

Martinez, the manager, said the recent turnover had nothing to do with the climate at city hall.

“People change jobs for all sorts of personal reasons: to live closer to home, for higher pay,” he said. “I don’t know that we’re experiencing it any more than anyone else.”

Regalado said there were explanations for each departure and firing. In most cases, he said, the city was better off.

“It would be unfair to say there is instability,” Regalado said. “The big picture is that we have been able to balance the budget and negotiate with the unions without raising taxes. If there was instability, we could not have done that.”

But Merrett Stierheim, who has served as both city and county manager and schools superintendent, said the turnover was significant and could create long-term problems for the city.

“Institutional knowledge comes from professionals with tenure,” Stierheim said. “You have a public works director who has been there for 10 years, you have continuity. The director gains the confidence of the commission. That gives him the ability to do his job well.”

Constant change might also discourage people from applying for vacant positions, Stierheim said.

“Why would people want to go there when they could choose to go to more stable organizations?” he said. “That makes it harder to attract someone who has really done their homework.”

The turnover hasn’t been limited to the top. Capital improvements, human resources and public works have each lost at least two assistant directors.

To Commission Chairman Francis Suarez, the steady stream of transitions in the finance department has been most troubling.

With Petty’s departure and the resignation of treasurer Mirtha Dziedzic in August, there are 10 vacancies in the department, city records show. Larned, the chief financial officer, threatened to quit this summer, less than a year into her tenure. She was talked into staying.

Meanwhile, the department has been dealing with two separate investigations by the U.S. Securities and Exchange Commission, and is trying to wrap up the $45 million bond issue on a tight deadline.

“This is one of our most critical departments, and there is no consistency,” Suarez said. “That’s something that needs to change.”