Philip B. Banks III, New York City’s deputy mayor for public safety, has resigned, Mayor Eric Adams said on Monday morning, making him the sixth senior administration official to leave City Hall in the past month.

His departure comes amid an exceptional level of turmoil at the highest levels of city government, as four federal investigations envelop Mr. Adams and his inner circle, and after prosecutors unsealed a five-count corruption indictment against the mayor.

On Sept. 4, federal investigators seized the phones of Mr. Banks, as part of an investigation into a possible bribery scheme.

As part of the same inquiry, investigators also seized the phones of Mr. Banks’s brother David C. Banks, the since-resigned schools chancellor, and Sheena Wright, the schools chancellor’s wife and the first deputy mayor. Ms. Wright is expected to resign imminently.