Federal prosecutors in Manhattan told a judge on Friday that they would drop a bribery case against Brian A. Benjamin, New York’s former lieutenant governor, following the death of a key witness.

The decision lifts a cloud that has followed Mr. Benjamin, a Democrat, since April 2022 when the government first accused him of funneling state money to a real estate developer in exchange for campaign contributions. The charges, announced in a splashy news conference, forced Mr. Benjamin to resign and all but ended his political career.

The Supreme Court declined to dismiss the case in December, and it had appeared as if Mr. Benjamin might finally face trial.

But on Friday, prosecutors wrote to the judge overseeing the case, J. Paul Oetken, that they no longer saw a path to proving their allegations after the death of the developer, Gerald Migdol. Mr. Migdol had pleaded guilty to related charges and was cooperating with the government before he died in February.

“Based on a review of the evidence in the case, and in light of the death of cooperating witness and co-defendant Gerald Migdol,” the prosecutors wrote, “the government has determined that it can no longer prove, beyond a reasonable doubt, the charges in the indictment.”

Mr. Benjamin had maintained his innocence, and in a statement, he thanked prosecutors for dismissing the case after what he called a “painful journey.” He said he had represented both his State Senate district and the state “with honor and integrity.”

In their own statement, Mr. Benjamin’s lawyers called the government’s move a “vindication.” They said it was “a timely reminder of the Rev. Dr. Martin Luther King Jr.’s famous words: ‘The arc of the moral universe is long, but it bends toward justice.’”

The lawyers — Barry H Berke, Dani R. James and Darren LaVerne of Gibson Dunn — had met privately with prosecutors from the U.S. attorney’s office for the Southern District of New York on Monday, according to Mr. Berke and Ms. James. They asked the officials to drop the case, and to do so before the current administration left office.

A spokesman for the Southern District declined to speak about the case.

Mr. Benjamin, 48, had been considered a rising star when Gov. Kathy Hochul picked him from the State Senate to become her lieutenant governor in August 2021. The selection made him her No. 2, and gave Mr. Benjamin a platform to advance his own political ambitions.

The federal indictment changed all that. Prosecutors charged that Mr. Benjamin had used his State Senate office to secure a $50,000 grant for a Harlem nonprofit run by Mr. Migdol. In exchange, Mr. Migdol helped arrange thousands of dollars in illegal contributions to Mr. Benjamin’s campaigns, prosecutors said.

Mr. Benjamin has suggested in recent years that he might be interested in re-entering public life if his legal case was cleared. But it was not immediately clear if he had plans to do so.

Jonah E. Bromwich and Jeffery C. Mays contributed reporting.