Opening a new chapter in an infamous stamp-world mystery, a valuable "inverted Jenny" stamp has surfaced six decades after it was stolen from a collectors' convention.

The stamp — one of the world's most famous pieces of postage — was among four of its kind taken from a 1955 collectors' convention. While two were recovered over 30 years ago, there had been no sign of the others until this one was submitted to a New York auction house this month and authenticated.

"It's one of the most notorious crimes in philatelic history, and there's a piece of the puzzle now that's in place," said Scott English, the administrator of the American Philatelic Research Library, which owns the stamp and is working with auctioneers Spink USA and federal authorities to recover it.

The would-be consigner, a man in his 20s who lives in the United Kingdom, said he'd inherited the stamp from his grandfather and knew little about it, said George Eveleth, head of Spink USA's philatelic department. He said authorities had told the auctioneers not to release the name of the consigner, who is in his 20s.

While it's unclear whether the man can shed any light on the long-cold trail to the thieves, the stamp was accompanied by an intriguing item: a 1965 letter about a monetary loan from a noted stamp dealer to a well-known auctioneer, both now dead, Eveleth said. The letter isn't necessarily connected to this stamp, however.

Still, the Bellefonte, Pennsylvania-based philatelic library hopes the stamp's discovery could lead to new clues.

"We're going to remain optimistic," English said. "Because think about it: Here we are, 61 years later, and a stamp has appeared."

Worth 24 cents when issued in 1918, inverted Jenny stamps fetch hundreds of thousands of dollars today. While other stamps are rarer, the Jenny is one of few that is readily recognized even by non-collectors, Eveleth said.

It made its way into popular culture in movies such as 1985's "Brewster's Millions," in which Richard Pryor's character uses one to mail a postcard, and television shows including "The Simpsons," in which Homer Simpson finds but disregards a sheet of them at a flea market. The Postal Service issued a commemorative inverted Jenny stamp in 2013.

The original was made to celebrate the launch of U.S. air mail. Some were printed with the Curtiss JN-4H "Jenny" biplane inverted, and a savvy customer bought a 100-stamp sheet before anyone realized the error.

Over the years, they were separated, coveted, counterfeited and narrowly saved from the blitzkrieg of London in World War II and from a flood in Wilkes-Barre, Pennsylvania.

A block of four was on loan to the American Philatelic Society when stolen from a display case at its 1955 convention in Norfolk, Virginia. The lender, who died in 1980, gave her rights to the stolen stamps to the society, which shares some ties with the American Philatelic Research Library.

Two of the Jenny stamps were recovered in the '70s and '80s from different Chicago stamp connoisseurs, who said they'd bought the stamps from people who had since died or whose names they didn't know, according to a 2014 article in American Philatelist, the society's journal.