Throughout all of this, Mr. Christie and his top spokesman, Michael Drewniak, repeatedly said the governor did not bother with trivial traffic decisions. On Dec. 2, Mr. Christie pilloried Democrats for playing politics. “I moved the cones, actually, unbeknownst to everybody,” he said with sarcasm.

The fallout began on Dec. 6, when Mr. Wildstein submitted his resignation from the Port Authority, explaining it as something planned but hastened by the “distraction” of the “Fort Lee issue.”

The cover story itself, though, began to unravel once Mr. Foye and bridge officials testified on Dec. 9. Mr. Foye said he knew of no bridge study. The other officials portrayed the notion as senseless. They said they were given three days’ notice to close the lanes, something that normally would involve years of planning. They were instructed not to tell anyone, including Fort Lee officials and Mr. Foye, they said, and complied out of fear of reprisals.

On the day of the hearings, The Wall Street Journal reported, Mr. Christie had called Mr. Cuomo to complain that Mr. Foye was pushing too hard to get to the bottom of the closings. Mr. Christie denied he had called Mr. Cuomo. The next day, the office of the Port Authority’s inspector general opened an investigation into the closings.

On Dec. 13, Mr. Baroni quit. Before going out to a news conference where the resignation would be announced, Mr. Christie decided, finally, to question his aides about whether they had any culpability. He gathered most of his senior staff inside his State House office and issued an ultimatum: They had an hour to confess any involvement with what had happened at the bridge or knowledge of who was behind it. None did. At the news conference, he praised Mr. Baroni for his service. He said no members of his staff had anything to do with the lane closings and the whole matter had been “sensationalized.”

On Wednesday, when emails emerged that had been subpoenaed by the Assembly, the truth became evident: This was always rank political payback.

The next day, Mr. Christie said he had been deceived and was “humiliated.” He fired Ms. Kelly, whom he called “stupid,” and severed ties with Mr. Stepien, his former campaign manager. The United States attorney for New Jersey began a preliminary inquiry. Then, Governor Christie traveled to Fort Lee to apologize to Mayor Sokolich. His arrival, accompanied by an onslaught of reporters and photographers, snarled traffic once again in the borough.