UFO investigators are looking at claims that President Truman and his personal bodyguard secretly visited the scene in July 1947, and were promised by a leading military official that there would be no trace left of the crash.
The Roswell myth has been at the heart of the UFO scene since in July 1947 the military sensationally announced in a press release it had found the remains of a crashed flying saucer in the desert nearby.
But the following day it retracted the statement, saying it was in fact a damaged US Air Force air balloon.
Witnesses later came forward to say there had been alien bodies within the “crashed craft”, which along with the wreckage were then taken to the mysterious top-secret Area 51 military base in Nevada.
The conspiracy theories surrounding the events remain today.
The allegations were yesterday made to the US-based Mutual UFO Network (MUFON), which keeps a global database of alleged UFO and alien sightings.
It carries out investigations into some of the reports it receives.
In the report to MUFON an unnamed source said: “My Uncle was personal bodyguard to Harry S Truman in 1947.
“They both went to Roswell at the insistence of President Truman in July 1947 after sneaking out of White House disguised as press.
“My uncle said they met a Major Easley at crash site.
“Major Easley promised the President that nothing from the crash would remain.”
Express.co.uk discovered a man has made similar claims on Facebook.
William Sells, from Noblesville, Indiana, whose profile says he is a retired “specialist” at the National Security Agency (NSA), said his uncle Wayne Schell had been personal bodyguard to President Truman, and had told him in the 1960s about the secret operation, which involved the use of a “double” of President Truman.
Mr Sells says he also previously held a “top-secret SI crypto clearance from the NSA.”
He posted: “Harry and him left the White House in disguise to the crash site after Truman saw debris at Andrews Air Force Base (in Prince George’s County, Maryland).
“The secret service instituted Operation Doppelganger and provided Harry Truman’s double to make sure the press was unaware of Harry’s real location.
“At first I did not believe him (Mr Schell) until we opened his military footlocker in his bedroom after his death around 1969.
“In there were letters from FDR and Truman along with glossy photos of the Yalta Conference with Churchill, Stalin and FDR.”
He said his uncle lived in Middletown, Indiana, and ran a dairy farm after his secret service work.
He added: “He told me that Roswell was extraterrestrial and that the military swept the site.
“They met a Major named Edward Easley at the site and he promised Truman that nothing would remain and nothing would be said.”
Express.co.uk could find no other record of a Wayne Schell linked to President Truman.
It is well documented, and among UFO circles, that Major Edwin Easley was the provost marshal at the Roswell Army Air Field at the time of the alleged crash and that he was responsible for base security.
Conspiracy theorists claim that dead aliens were found in the wreckage of the alleged crashed flying saucer but they were secretly hidden at a US air force base.