 FAKE: The microphone used to record Dr. Martins confession is a  desktop shortwave radio pushbutton microphone. When the button is  up, it acts as a speaker. You have to depress the "talk" button on  the base in order to transmit. The FBI agent just holds the neck of  the mike stand without depressing the "talk" button. This type of  microphone was incompatible with tape recorders then in use in the  1950s.