When the federal authorities last week seized the phones of top City Hall officials in New York it was another stunning public move by investigators who had already taken Mayor Eric Adams’s devices searched his aides’ homes and issued subpoenas to members of the mayor’s staff.

The intensity and sheer volume of the federal scrutiny has raised urgent questions about the scope of what federal agents are seeking and how much longer they intend to seek it especially with the Democratic mayoral primary approaching next year.

A representative of the U. S. Attorney’s office for the Southern District of New York which is conducting most of the investigations declined to answer questions about the inquiries or say whether the office would issue a statement if no charges were filed as it has done with other recent investigations.

But interviews with four former federal prosecutors including two who headed the public corruption unit within the same office that is investigating the Adams administration said that U.S. Investigators would not have taken such significant steps if they did not believe there was sufficient reason for doing so.

The scope of the seizures signals an intensity of interest from federal investigators and a complete distrust of the so called cooperation from the city said Daniel C.Richman a Columbia Law School professor who worked as a federal prosecutor in Manhattan in the late 1980s and early 1990s.

The actions he said also point to the extent of development of the case. Across the cases investigators appeared to be ranging widely through the administration examining not just the mayor but the heads of the police and the schools and some of Mr.Adams’s top deputies: Agents on Wednesday took the phones of Edward Caban the police commissioner as well as the first deputy mayor the schools chancellor and others.

They searched the home of a consultant who is a brother both of the schools chancellor and one of Mr.Adams’s deputy mayors. Since you have to deal with the police commissioner and his force constantly it takes a real commitment to a particular case and a real belief that you’re onto something to seize his phone Mr.Richman said. Prosecutors have opened several investigations. The actions last week appear connected to two inquiries by the U.S. Attorney’s office for the Southern District in Manhattan. One appears to be focused on senior City Hall officials and the other on the police commissioner.

Separately federal prosecutors in Manhattan have been investigating whether Mr. Adams and his campaign conspired with the Turkish government to receive illegal foreign donations during the 2021 election.

Again the full scope of that investigation is unclear.