How much power does the mayor of a city have over criminal cases?
Can a mayor tell the Chief of Police or the city attorney's to not bring an indictment for a criminal charge, even if a law has been violated pertaining to state law?
While mayors have various levels of power, depending on the structure of the government of their city, mayors do not have the formal right to decide when to bring a criminal case against a particular person.
In the US legal system, it is prosecutors who decide who gets charged with a crime or not. The general procedure is that police arrest a person, gather evidence, and present that evidence to the prosecutor. It is then up to the prosecutor to bring charges or to drop the case.
It is, of course, conceivable that a mayor or other high official could put pressure on prosecutors to drop a case, but there is no legal mechanism by which they can order the prosecutors or the police to do so.