WASHINGTON — Just days into his new position as President Trump’s national security adviser, Michael T. Flynn found himself in a meeting that any White House official would dread. Face to face with F.B.I. agents, he was grilled about a phone call he had had with Russia’s ambassador.

What exactly Mr. Flynn said has not been disclosed, but current and former government officials said on Tuesday that investigators had come away believing that he was not entirely forthcoming. Soon after, the acting attorney general decided to notify the White House, setting in motion a chain of events that cost Mr. Flynn his job and thrust Mr. Trump’s fledgling administration into a fresh crisis.

Mr. Flynn’s rise and fall followed familiar patterns in Washington, where ambitious figures secure positions of great authority only to lose them in a blizzard of contradictions, recriminations and scandal. But rarely has an official at such a high level risen and fallen in such a dizzyingly short time, in this case just 24 days after Mr. Flynn arrived in the West Wing to take his corner office.

Given his short stay at the top, Mr. Flynn’s case might be quickly forgotten as an isolated episode if it did not raise other questions, particularly about what the president knew and when. Even more broadly, it underscores lingering uncertainty about the relationship between the Trump administration and Vladimir V. Putin’s Russia, a subject of great interest given American intelligence reports of Moscow’s intervention in last year’s elections in the United States.