In April 1942, Cvetic came to the attention of the FBI which offered him the opportunity to penetrate the American Communist Party as part of their broader anti-communist efforts. Cvetic quickly agreed, and by the end of 1942, was considered suitable material for membership in the Pittsburgh branch CPUSA, his membership being granted to him in February, 1943. Shortly after his joining the party, Cvetic was offered weekly compensation in the amount of $15, which was increased to $35 per week in late 1943, then $65 by 1947. By 1948 he was earning $85 per week for his work, and although he continually pressured the Bureau to increase his salary to $100 and threatened to quit if his requests were not granted, FBI Director J. Edgar Hoover rebuffed his requests.