Leonard Delue Secret Service Investigators Ad, Denver, 1934
In this time period, private investigative services were often called "Secret Service Investigators." Let's see what else we can quickly find out about Leonard Delue and his Secret Service Investigators from the ad. Note the logo. It's looks like a combination of the Masonic Mason logo with a finger print in the middle. We checked and sure enough, Leonard Delue was a Mason in 1934. However, further checking reveals this logo to the the logo of the International Association for Identification (IAI) which Leonard Delue was a member of. The International Association for Identification was started in the 1915 and was first called the International Association for Criminal Identification. In 1918, at the fourth annual conference, the word "Criminal" was dropped from the name of the Association, in recognition of the volume of noncriminal work done by identification bureaus.

Note that Leonard Delue listed both his day office phone and night phone. Note also the phone numbers. In 1934, there was only a two digit prefix. KE-1397 would get the service during the day and FR-6348 would connect you at night to what was Leonard Delue's home phone. We checked a 1934 phone book for Denver and sure enough, there was a Leonard Delue listed at a home address (indicated with a "r" for residence) of 310 Colorado Blvd. with a phone number of FR-6348. Right below Leonard Delue's residential listing was his business listing with the phone number and address as above. There was also a notation after the listing that states, " If no answer to above call MA-1718." Try and get that kind of detailed listing from the phone company today! There is no doubt that Leonard Delue took every step he could not not miss any phone calls. The Gas And Electric Building still stands today in downtown Denver. Below is a photo of the building.

An early postcard of the Gas And Electric Building. It was the "good" business address to have in 1934.

The Gas And Electric Building in downtown Denver as it stands today. The building has been renovated.

Above is a Satellite image of the Gas And Electric Building in downtown Denver.
Wouldn't Leonard Delue be highly impressed with that technology today.


From The Ralph D. Thomas PI Vintage Collection
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