One juror, Michael G. Meyer, said that while some jurors were “very disturbed” by Mr. Craig’s conduct, “the law was presented to us in a very narrow fashion” that ruled out conviction.

Because the statute of limitations had run out to hold Mr. Craig accountable for any actions before October 2013, jurors were limited to considering whether he deceived federal officials during the three-month period that followed. Mr. Meyer said that four jurors switched their votes from guilty to not guilty after the panel sent a note to the judge to verify the limited time frame.

“Based on that very narrow thing, we couldn’t find anything he had done that warranted finding him guilty,” he said. Mr. Meyer added that Mr. Craig, in testifying in his own defense, came across as “very credible.”

Mr. Craig’s defense team insisted that prosecutors had concocted a charge out of a few minor omissions of facts that Mr. Craig was never under any obligation to reveal. “Mr. Craig is not the kind of person who would lie to a U.S. government agency, not after a 50-year career based on character and trust,” another of his lawyers, William Murphy, told the jurors.

Prosecutors said Mr. Craig gave in to hubris and self-interest, hiding the truth of his media contacts, not only from the Justice Department, but from his own firm’s general counsel. Fernando Campoamor-Sanchez, one of the prosecutors, described Mr. Craig’s final letter on the matter to the Justice Department as a “masterpiece” of lies and half-truths.

“If you read the letter,” he argued, “you will find contempt for the FARA unit.”

The FARA unit’s inquiry concerned a 2012 report that Mr. Craig and his law firm — Skadden, Arps, Slate, Meagher and Flom — produced for the Ukrainian government, then led by Viktor F. Yanukovych. Mr. Craig and his fellow lawyers were hired to review Ukraine’s prosecution of an opposition leader who had recently been sentenced to seven years in prison on corruption charges — a case that the United States and other Western nations had condemned as politically motivated. Mr. Yanukovych and his allies hoped the Skadden report would blunt criticism of the prosecution from the West.

The report, which earned the law firm $4.6 million, concluded that while the opposition leader’s rights had been violated at trial, her conviction was backed by evidence.