New York City’s interim police commissioner said late Saturday that federal agents had searched his homes and seized material from them the day before.

The interim commissioner, Thomas G. Donlon, whom Mayor Eric Adams chose to lead the Police Department only nine days ago, said the search warrants executed by the agents were unrelated to the department, which has been caught up in a series of federal criminal investigations that are swirling around the mayor’s administration.

“They took materials that came into my possession approximately 20 years ago and are unrelated to my work with the New York City Police Department,” Mr. Donlon said in a news release issued by the department shortly after 11 p.m. “This is not a department matter, and the department will not be commenting.”

Mr. Donlon did not offer details about the materials that were seized, nor did he say how many homes had been searched or where they were. Nor was it clear which agency conducted the searches; the F.B.I.’s New York office said early Sunday that it would not comment on the matter.

It is unclear what job Mr. Donlon may have held when the material the agents sought came into his possession.

From 2002 to 2003, he was in charge of the F.B.I.’s New York Counterterrorism Center, and he worked for the agency’s National Threat Center until 2005, according to a news release from a New York State Senate committee that later vetted his nomination to lead the state’s Office of Homeland Security. Mr. Adams, a state senator at the time, led the committee. In 2005, Mr. Donlon joined Credit Suisse.

When Mr. Adams announced Mr. Donlon’s appointment as interim commissioner this month, he called him “an experienced law enforcement professional who has worked at the local, state, federal and international levels.”

Mr. Donlon, for his part, promised to “uphold the highest standards of integrity and transparency.”