agents seized Mayor Eric Adams’s electronic devices early this week in what appeared to be a dramatic escalation of a federal corruption investigation into whether his 2021 campaign conspired with the Turkish government and others to funnel money into its coffers, two people with knowledge of the matter said.

Mr. Adams responded to news of the raid by abruptly returning from Washington, D.C., where he had only just arrived for a day of meetings with White House and congressional leaders regarding the migrant influx, an issue he has said threatens to “destroy New York City.”

The warrant also sought records about donations from Bay Atlantic University, a Washington, D.C., college whose founder is Turkish and is affiliated with a school Mr. Adams visited when he went to Turkey as Brooklyn borough president in 2015.

In September, Eric Ulrich, Mr. Adams’s former buildings commissioner and senior adviser, was indicted by the Manhattan district attorney, Alvin L. Bragg, on 16 felony charges, including counts of bribetaking and conspiracy.

In July, Mr. Bragg indicted six people, including a retired police inspector who once worked and socialized with Mr. Adams, on charges of conspiring to funnel illegal donations to the mayor’s 2021 campaign.

In deciding not to bring charges, the acting United States attorney, Joon H. Kim, cited “the particular difficulty in proving criminal intent in corruption schemes where there is no evidence of personal profit.” Mr. de Blasio received a warning letter about those activities from the city’s Conflicts of Interest Board.

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