On a cold December morning in Denver, CO, 1922, a Buick touring car pulled up behind an armored car in front of the Denver Mint. Four gunmen emerged from the Buick and demanded the money that was being loaded into the armored car. One of the Mint guards, a veteran of the police force, was killed during the ensuing shootout. The case wouldn't be "solved" until nearly 15 years later and the details of it sound closer to a gangster movie than a real life crime.