After the trial, jurors declined to comment — except one who, as she strode away from the courthouse, offered that she was “happy it’s over.”

The United States attorney in Manhattan, Geoffrey S. Berman, said in a statement that Mr. Percoco had sold “something priceless that was not his to sell: the sacred obligation to honestly and faithfully serve the citizens of New York.”

Much of the government’s narrative of the bribery schemes revolved around Todd R. Howe, a disgraced former lobbyist and longtime Albany insider, who prosecutors said engineered the bribes from the executives to Mr. Percoco.

Mr. Howe, who had pleaded guilty to eight felonies and was cooperating with prosecutors, described how Mr. Percoco helped COR Development, the Syracuse company that employed Mr. Aiello and Mr. Gerardi, evade a costly union requirement on a development, and wangled a pay raise for Mr. Aiello’s son, who worked in state government. In return, Mr. Howe said, Mr. Percoco pressured the executives to help his wife land the job with the power company or to funnel thousands of dollars a month in covert payments.

But Mr. Howe at times seemed poised to be the prosecution’s downfall, rather than its linchpin.

In early February, he was arrested midway through his testimony, after admitting during cross-examination that he had attempted to defraud his credit card company — after signing his cooperation agreement with the government.

The shocking development bolstered defense arguments that Mr. Howe was a self-interested liar whose testimony could not be believed; lawyers monitoring the case called the arrest a prosecutor’s worst nightmare.

Prosecutors also suggested that Mr. Percoco had violated New York State election and ethics laws by continuing to intervene in state business even after he left to work in the private sector. Witnesses said they had often seen Mr. Percoco in Mr. Cuomo’s New York and Albany offices even after he was no longer a state employee. Public records indicate that Mr. Cuomo was often in the office at the same time.