This spring, the F.B.I. and the Justice Department made an all-out push involving hundreds of employees to scour the Jeffrey Epstein files with a single goal in mind — find something, anything, that could be released to the public to satisfy the mounting clamor from the angry legions of President Trump’s supporters.

But after devoting countless hours to the project, working at times around the clock searching databases, hard drives, network drives, cabinets, desks and closets, the bureau and the department finally acknowledged this month that they had little to show for their efforts. They came to realize, for instance, that there was no specific “client list,” which previous investigators had known years ago.

Those conclusions, announced in a memo earlier this month and then repeated this week in a statement by a Justice Department official, capped a frenetic scramble to sort more than 100,000 pages of materials related to Mr. Epstein, the disgraced financier who died in prison six years ago awaiting trial on sex-trafficking charges. During the inquiry, Justice Department officials diverted hundreds of F.B.I. employees and federal prosecutors from their regular duties to go through the documents at least four times — including once to flag any references to Mr. Trump and other prominent figures.

The bureau’s own expert document reviewers raised concerns at one point that the investigation was not only being rushed, but could also violate laws and internal protocols put in place to protect against sensitive information about witnesses, child victims and grand jury material from being released.

Details of the review were based on accounts by three former F.B.I. and Justice Department officials who spoke on the condition of anonymity because of fears of retaliation. The New York Times also obtained a summary of the process as described by one senior bureau official to the Senate Judiciary Committee.

The expansive and ultimately fruitless effort to scrutinize the files reflects the obsession within the Trump administration and Mr. Trump’s political base with Mr. Epstein — a fixation that several top administration officials helped fuel themselves before they entered government. The review appeared to be nearing an end in mid-April, shortly before Attorney General Pam Bondi briefed Mr. Trump that he was mentioned in the files.