The assertion by Elon Musk last month that Donald J. Trump was named in the F.B.I. files concerning the disgraced financier Jeffrey Epstein signaled a loud, public crack in the president’s support system.

That crack has become a chasm in recent days after the administration suddenly reversed course on its longstanding promises to reveal previously unknown details of the investigation into Mr. Epstein, who was awaiting trial on sex-trafficking charges before his death in 2019.

The remaining files, administration officials suggested, included a “client list” that many involved in the case insist never existed. Suddenly, some of Mr. Trump’s most ardent and outspoken supporters declared that they smelled a cover-up, even if they did not agree on who was involved or why.

Over the weekend, Mr. Trump urged his supporters to move on, imploring them on social media not to “waste Time and Energy on Jeffrey Epstein, somebody that nobody cares about.”

The still unfolding fallout from the Trump administration’s decision to keep the files secret highlights the ways in which Mr. Epstein is a more politically potent figure now than when he killed himself six years ago in a Manhattan jail cell.

What is the origin of the case?

Mr. Epstein paid teenage girls money to perform sex acts, and used his onetime girlfriend Ghislaine Maxwell to recruit and manage his stable of victims.