Crimebusting Technology in 1922.
In his quest to bring the Blonger Gang to justice,
Prosecutor Van Cise employed crimefighting techniques
that were cutting-edge in 1922.
Based partly on descriptions in Fighting the Underworld
Though its admissibility in court was debatable, Van Cise had a dictaphone (microphone) installed in the overhead light fixture of Lou Blonger's office. The device used four fifty-pound wet cell batteries, hidden in the attic above the office. The batteries were unreliable, and required frequent refilling with acid. Building up a new charge took up to twenty-four hours.
A wire strung across the street carried the signal to an office where a stenographer sat at the ready to transcribe any conversation. Though Van Cise considered "Mrs. Steno" inept, and her reports "meager in the extreme," the transcriptions proved a valuable hole card in prosecuting the case.
The Observation Post
Based on his experience on the front lines in France, Colonel Van Cise had an observation post constructed across the street from Blonger's downtown Denver office. Built high on a platform in the attic of a warehouse, a small room housed an agent with a powerful telescope. A brick was removed from the wall to grant a view of the office, and the inside of the room was painted black, with double doors at the entrance, to prevent light from being visible from the outside looking in.
Lou's office in the American Bank Building
The Bandit Chaser
Here's a conceptual drawing of Denver's Bandit Chaser circa 1922.
And the real thing.