When an antiques collector stumbled across an old photograph at the bottom of a cardboard box, he had no idea about the great adventure that lay in store for him.

In a Californian antique store, Randy Guijarro is rummaging through a cardboard box. Then, right at the bottom, he stumbles across three old photos – before snapping them up for a bargain price. When he gets them home, however, he realizes that one of the pictures features a very familiar face.

Guijarro has always enjoyed collecting, with coins, comic books and sports cards all among his favorite memorabilia. Then when he met his wife, Linda, it was a match made in heaven. She was a fan of old photographs, and the pair loved sharing their interests with each other.

Image: Facebook/Fulton’s Folly Antiques Collective

In the summer of 2010, however, Randy’s hobby would take a turn that would change his life for good. Yes, one day he was passing Fulton’s Folly Antiques Collective, a store in the Tower district of Fresno, California. And, spotting an empty parking space out front, on a whim, he decided to go inside.

Image: Facebook/Fulton’s Folly Antiques Collective

At the store, the collector encountered two men who had recently purchased a storage unit at auction and were looking to clear it of what they believed to be junk. Among their possessions, moreover, was a cardboard box, and a curious Randy took a closer look.

Inside, Randy discovered three old photographs, all depicting 19th-century scenes. Deciding that he liked the look of them, he then offered the men everything that was contained in his pocket – a grand total of $2. What’s more, they accepted, and Randy returned home with three new additions to his collection.

Now among the three photographs was one that particularly stood out to Randy. A tintype of 20 square inches, it showed a group of figures engaged in a genteel game of croquet. However, when he took a closer look under a microscope, Randy realized that there was more to his find than first met the eye.

Amazingly, Randy became convinced that one of the men in the photograph was Billy the Kid, the iconic celebrity of America’s Wild West. “You could put a Winchester rifle in his hands,” he told The Guardian in 2015. “It was the hat, the stance, him leaning on a croquet stick. I thought, my lord, it’s Billy the Kid,” he added.

Stunned, Randy summoned Linda, and the pair began investigating deeper. What’s more, when they discovered that two other men in the photograph were the spitting images of Charlie Bowdre and Tom O’Folliard – both members of Billy’s notorious gang the Regulators – they knew they were on to something big.

For aficionados of the Wild West, there are few personalities as loved or as romanticized as Billy the Kid. Born as Henry McCarty in 1859, the future outlaw was in trouble with the law from a young age. Then after a spell in jail as a teenager, he escaped and went on the run.

Image: Center For Southwest Research, UNM Libraries

By sometime in 1877, McCarty had taken on the alias of William H. Bonney. And after killing a blacksmith in Arizona, he fled to New Mexico, where he hooked up with the Regulators. They were a group of cattle rustlers in the employ of John Tunstall, an English rancher. When Tunstall was then killed by rival gangs, it sparked a conflict known as the Lincoln County War.

As the rival factions battled one another for control of the region, Bonney’s infamy grew. Now dubbed Billy the Kid by the press, he found himself blamed for every crime that the Regulators committed. Then, in 1878, William J. Brady, the County Sheriff of Lincoln, and two other men were killed in a shootout with the gang.

Image: Center For Southwest Research, UNM Libraries

Now charged with murder, Bonney was finally captured in December 1880 and was sentenced to hang the following May. Dramatically, though, that April, he escaped from jail yet again. For two months he managed to evade capture, too, before Sheriff Pat Garrett finally tracked him down to Fort Sumner, NM, in July 1881.

Image: Center For Southwest Research, UNM Libraries

Recognizing the man who had eluded the law for so long, Garrett struck Bonney down with a fatal gunshot to the chest. However, there were some who refused to believe that the outlaw was really dead. In fact, claims that Bonney’s death was somehow faked continue to be investigated to this day.

For a figure so rooted in history, myth and popular culture, little of Billy the Kid’s legacy remains. Indeed, among the few relics that can be positively linked to the outlaw is a single photograph, taken around 1880. In 2011 an American businessman bought the original for $2.3 million.

Perhaps unsurprisingly, then, finding another Billy the Kid photograph has become something of a Holy Grail to those interested in the history of the Wild West. So when the Guijarros thought they had identified the outlaw in their thrift store find, it was quite the exciting discovery.

After a year of researching the photograph, Randy and Linda began trying to spread the word about their discovery. However, they soon found that not everyone was quite so willing to believe. Then in 2012 they took the snap to Witherell’s Old West Show in Northern California’s Grass Valley.

There, the couple tried to bring their find to the attention of Brian Lebel, the man who had brokered the deal on the 1880 photograph. Unfortunately, though, they claim that another expert arrived and dismissed their discovery out of hand, pointing out that they had no proof that the man in the picture was actually Billy the Kid.

It was the start of a lengthy process that would consume the next three years of Randy and Linda’s lives. Eventually, they pulled together a team of specialists, using means such as facial recognition software to try and prove that the photograph was the real deal. Then, in 2015, the National Geographic documentary Billy the Kid: New Evidence was released.

In the documentary, the evidence to support the photograph’s authenticity is laid out in full. However, some experts are yet to be convinced. “No one in our office thinks this photo is of the Kid,” wrote True West magazine in 2015.

That said, these naysayers don’t seem to have stood in the way for the Guijarros and their pursuit of fortune. In fact, in the same month that the documentary was released, California auction house Kagin’s deemed the photo authentic and insured it for $5 million. Meanwhile, Randy would like his discovery to inspire a movement. “I hope this prompts others out there to look into trunks and attics,” he said, “because there are so many lost treasures out there.”