Did you know that back in the 1920's Denver had one of the top Bunko Squads in the U.S. Colorado District Attorney Philip Van Cise put together a top notch squad to help him gather evidence and capture the "Million-Dollar Bunko Ring" headed by Lou Blonger. A large group of confidence men were operating a scam being pulled on tourists unfamiliar with Denver. Various sums of money were being extorted from the tourists. Van Cise feared that Denver police were corrupt and involved with the con men, so he raised money privately from some of Denver's leading families. This money allowed Van Cise to hire out-of town investigators to gather evidence.
Robert Maiden took leave from the Federal Narcotics Bureau to come to Denver and work on the bunko case with Andrew Koehn and A. B. Cooper. They installed a Dictaphone "bug" in the room where the suspects operated, set up surveillance in the Albany Hotel where the tourist were being lured and used powerful telescopes to spy upon the room where the suspects operated. They also "bugged" the telephones.
After Van Cise had gathered enough evidence, he arrested the gang of crooks in August of 1922. The result ended in convictions of the gang members, though several jumped bail and escaped.
These photos are from the archive collection of Robert Maiden http://catalog.denverlibrary.org/search/title.aspx?pos=1 
Showing Lou Blonger and Adolph Huff members of the Million-Dollar Bunko Ring