Conspiracy theorists have long clamored for what they hope will be evidence to prove that the government covered up the truth about the assassination. This week, Roger J. Stone, a friend of Mr. Trump’s, told Alex Jones, the radio host and conspiracy theorist, that Mr. Stone had directly urged the president to release all the documents.

“I had the opportunity to make the case directly to the president of the United States by phone as to why I believe it is essential that he release the balance of the currently redacted and classified J.F.K. assassination documents,” Mr. Stone said on Mr. Jones’s radio program.