Donald Trump has ordered the release of thousands of classified files on the assassination of President John F Kennedy.
The 1963 killing in Dallas is the source of one of the most well-known conspiracy theories of modern times.
Lee Harvey Oswald was said to be the gunman but was shot dead himself two days after JFK’s killing.
Theories that have persisted include that there was a second shooter and that it was a plot connected to communist Cuba.
President Trump had promised during his election campaign to make public the last withheld records on the case.
He signed an executive order to that effect on Thursday, telling reporters “everything will be revealed”.
The order will also declassify remaining federal records on the assassinations of civil rights icon Martin Luther King Jr in 1968, and JFK’s brother, Robert F Kennedy, who was shot dead the same year while running for president.
Mr Trump had promised to uncover the documents during his first term but agreed with CIA and FBI pleas to keep some secret.
JFK’s nephew, Robert F Kennedy Jr, is the president’s pick for health secretary and has said he is not convinced just one man was behind his uncle’s murder.
After signing the order, Mr Trump ordered the pen to be given to RFK Jr.
However, JFK’s grandson Jack Schlossberg hit back at President Trump’s executive order, saying there was “nothing heroic” about it.
“The truth is a lot sadder than the myth – a tragedy that didn’t need to happen. Not part of an inevitable grand scheme,” he wrote on X.
“Declassification is using JFK as a political prop when he’s not here to punch back.”
The attorney general and head of national intelligence must now come up with a plan in the next 15 days to declassify the JFK files, and within 45 days for the other cases.
It is therefore unclear exactly when they will see the light of day – and experts on the case are not holding their breath for any major revelations.
Only a few thousand of the millions of records on the JFK case are still to be fully declassified.
“There’s always the possibility that something would slip through that would be the tiny tip of a much larger iceberg that would be revealing,” said Larry J Sabato, author of a book on Kennedy.
“That’s what researchers look for. Now, odds are you won’t find that but it is possible that it’s there.”
The executive order is the latest in a slew signed by Mr Trump in his first few days back in the White House.
Others include leaving the Paris Climate Agreement, renaming the Gulf of Mexico the Gulf of America, and terminating government diversity programmes.
However, his attempt to end birthright citizenship for the children of undocumented migrants has already been temporarily blocked by a judge.
