The Trump-era special counsel who scoured the Russia investigation for wrongdoing gathered evidence that undermines a theory pushed by some Republicans that Hillary Clinton’s campaign conspired to frame Donald J. Trump for colluding with Moscow in the 2016 election, information declassified on Thursday shows.

The information, a 29-page annex to the special counsel’s 2023 report, reveals that a foundational document for that theory was most likely stitched together by Russian spies. The document is a purported email from July 27, 2016, that said Mrs. Clinton had approved a campaign proposal to tie Mr. Trump to Russia to distract from the scandal over her use of a private email server.

The release of the annex adds new details to the public’s understanding of a complex trove of 2016 Russian intelligence reports analyzing purported emails that Russian hackers stole from Americans. It also shows how the special counsel, John H. Durham, went to great lengths to try to prove that several of the emails were real, only to ultimately conclude otherwise.

The declassification is the latest disclosure in recent weeks concerning the Russia investigation. The wave has come as the administration is seeking to change the subject from its broken promise to release files related to the disgraced financier Jeffrey Epstein.