Auction director Dave Amerman admitted that the signed album, John and Yoko Ono’s Double Fantasy release, had “stirred emotions” since it was listed for sale during an interview with Express.co.uk.
He believes the piece could bear John Lennon’s “final signature”, which was obtained after Chapman approached the singer-songwriter five hours before his death.
The murderer was a fan of The Beatles but had grown frustrated by the band’s anti-religious lyrics and claimed a passage from The Catcher in the Rye inspired his attack.
Chapman felt John’s innocence would be preserved by death – similar to the novel’s protagonist Holden Caulfield who wanted to preserve children’s innocence before he changed his mind.
He approached John at around 5pm, which was “not uncommon for fans” who often waited outside his hotel “for the chance to meet” the singer “or seek an autograph”.
Five hours later, Chapman shot the Beatle after “waiting in an archway entrance” for him to return and fired five shots after “the couple passed him on their way into the building”.
Mr Amerman told Express.co.uk: “This John Lennon item is one of his last, if not his final, ever signatures, we are selling this to honour his legacy for the 40th anniversary of his death.
“We anticipate a seven-figure sale, it should be the most expensive album ever sold and we do expect one-million-dollars-plus.”
The album bears John’s name and the year 1980, which he penned on Yoko’s neck in blue pen, but it also holds other markings added after the killing.
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“I’ve actually spoken to an attorney who can confirm that this was the album she has the receipt for as evidence and showed fingerprints on the dust covers were from Chapman.”
It was returned to Mr Michael after the investigation concluded and was then “kept under his bed for 18 years” before it was first sold in 1998.
Mr Amerman believed this was the “last chance” for an individual to purchase the item as it wasn’t going to be listed again “any time soon”.
He told Express.co.uk: “With auctions, emotions are what drives pieces to sell for record-prices and obviously this will stir emotions of all sorts.
“This is a historically important artefact and John Lennon’s signature was the toughest Beatles autograph to get.
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“Although there is an unfortunate history behind it, we are not condoning or advocating what occurred, we’re viewing this as a tribute to life and career.
“The situation was unfortunate, horrible and tragic but the item still is what it is and is an incredible one-of-a-kind piece.”
On Twitter, fans were furious over the sale – some demanded that it should be “burned” and another questioned: “Who the f*** would want that!”
John’s former bandmate, Rod Davis, of The Quarrymen, told Express.co.uk that you “can’t stop people even if it’s bad taste” and felt some may “want it out of respect”.
For more information or to register a bid, visit here.