(Newser) – A weird twist in what are being painted as two of the largest bank heists in Colorado history: Less than a week after two bank robbers dubbed the "Trash Talking Bandits" successfully made off with a $500,000 score from a Wells Fargo branch in Wheat Ridge, that same amount of money was returned, anonymously. The attorney who brought the cash to the FBI said he didn't even know what was in the bag, though authorities suggest to CBS Denver that Mike Pellow is staying mum to protect his client: the robbers themselves, or possibly their friends or relatives. Why it was returned is unclear, but the FBI agent at the helm of the case believes it's highly unlikely the robbers themselves returned the cash. "Possibly a family member found it and thought, 'Oh my God, I need to bring this to the authorities.'"

The robbers are thought to be behind another Jan. 21 heist of a separate Wheat Ridge branch, during which almost $1 million was taken. Their moniker comes from the insults they hurled at the bank's employees; in the June 17 robbery, one of them kicked a teller. In both instances, they were in and out of the bank vault in less than two minutes and burned the stolen getaway cars to destroy evidence. They also carried handguns and covered their faces, reports ABC7. Authorities are worried the aggressive behavior will become increasingly violent, and that has the FBI urging the person who handed over the money to come forward and reveal who's behind the heists. (Click to read about a guy who robbed a woman and then friended her.)

