American activities:

The Dies Committee also carried out a brief investigation into the wartime internment of Japanese Americans living on the West Coast. The investigation primarily concerned security at the camps, youth gangs allegedly operating in the camps, food supply questions, and releases of internees. With the exception of Rep. Herman Eberharter, the members of the committee seemed to support internment.
In 1938, Hallie Flanagan, the head of the Federal Theatre Project, was subpoenaed to appear before the committee to answer the charge that the project was overrun with communists. Flanagan was called to testify for only a part of one day, while a clerk from the project was called in for two entire days. It was during this investigation that one of the committee members, Joe Starnes, famously asked Flanagan whether the Elizabethan playwright Christopher Marlowe was a member of the Communist Party, and mused that "Mr. Euripides" preached class warfare.[4]
In 1939, the committee investigated leaders of the American Youth Congress, a Comintern affiliate organization.
Ironically, congressman Samuel Dickstein, vice-chairman of the respective committees, was himself named in Soviet NKVD documents as a Soviet agent.[5]