Ironically, he would serve his sentence at the same prison as two of the Hollywood Ten, whose convictions were obtained after Thomas's inquiries into the film industry.

Following his discharge from the military in 1919, Thomas worked in the investment securities and insurance business in New York City for the next 18 years.

[citation needed] In the post-war period, Thomas called for a rapid demobilization of the American military.

In May 1947, Thomas traveled to Hollywood to meet with film industry executives with a view to exposing what he believed was Communist infiltration of motion pictures content by members of the Screen Writers Guild.

These summonses led to the conviction and imprisonment for contempt of Congress of the "Hollywood Ten" who had refused to answer the Committee's questions, citing the First Amendment.

Prominent American columnists Jack Anderson and Drew Pearson were critical of Thomas and his committee's methods.

[9] Thomas refused to answer questions, citing his Fifth Amendment rights, the most common stance for which he had criticized accused Communists.

In an ironic twist, he was imprisoned in Danbury Prison where Lester Cole and Ring Lardner Jr., both members of the "Hollywood Ten" were serving time due to Thomas's inquiries into the film industry.