The Museums of Western Colorado’s Western Investigations Team has been attempting to crack the region’s unsolved mysteries since it was formed in 2005 as a collaboration between the consortium of museums and Colorado Mesa University.

Since then, the team has successfully proven the innocence of “Colorado Cannibal” ​Alfred Packer, a prospector who confessed to cannibalism during the harsh winter of 1874. And for the last seven years, they've turned their attention to an ongoing excavation site near the Western Slope region's Grand Junction municipality.

There, Joe Vaccarelli reports for The Daily Sentinel, the team found a piece of a 500-year-old pistol that might shed new light on Colorado’s Spanish colonial history.

The part is called a "dog," which is a spring-loaded arm used in a Spanish wheellock pistol. Testing revealed the pistol dates back to 1500 to 1600, before flintlock pistols and muskets were introduced.

Researchers say this is an unusual find. Most artifacts like this one have been found in Texas and New Mexico. It’s generally believed that the Spanish arrived in Colorado in the 1700s, but the discovery might push the timeline back by a century or more.

The team tells Smithsonian.com that they found the dog several years ago, but the piece only recently underwent metallurgical testing. The team has also unearthed the pistol’s trigger guard, made of iron rod.

He says there are a few possible explanations for how the pistol got to Colorado. Perhaps an illegal expedition by the Spanish brought the pistol part to the area or it's possible that a local native tribe traded for it. “We do know that most Spanish expeditions had to be approved, but there is a possibility that they arrived earlier than believed,” he says.

Unfortunately, the area where the dogg was found has experienced massive floods over the years “making it difficult to determine whether metals were traded or it arrived in an early expedition,” Bailey says.

The team has also found Spanish armor parts and other artifacts, including a rondel dagger popular in Europe in the late Middle Ages, at the site. The dagger is still undergoing testing.

If the team can find other parts of the pistol, like the butt plate or barrel, they could narrow down the time frame for the find as gun parts and designs were regularly updated, Bailey says.

For now, the team continues to work away at the mystery and will return to the dig later this year in search of more clues.