American baseball player and secret agent. The son of Russian immigrants, Berg played high school baseball in Newark, NJ., and at Princeton University, where he majored in languages. After graduation, the Brooklyn Dodgers signed him as a catcher, launching his 16-year baseball career. In 1934, under cover of a touring baseball player, he made films of Tokyo Harbor and Japanese military installations at the request of U.S. intelligence.

After leaving baseball, in 1941 Berg went on a factfinding mission to Latin America for Nelson Rockefeller, coordinator of Inter-American Affairs for President Roosevelt. At that time the FBI had jurisdiction over U.S. counterintelligence in Latin America, and it is probable that Berg gathered intelligence for the FBI.

In 1943 Berg joined the Office of Strategic Services (OSS). He parachuted into Yugoslavia to assess the anti-German efforts of Josip Broz Tito's partisans. He also entered German-occupied Norway as part of the Allied effort to find and destroy a heavy-water plant that was part of the unsuccessful German effort to build an atomic bomb.

Berg's OSS work took him to Bern, Switzerland, where he met with Allen W. Dulles, then the chief of OSS intelligence there, and later the Director of Central Intelligence. Berg later worked for the North Atlantic Treaty Organization (NATO) and is believed to have continued to accept intelligence assignments during the 1950s and 1960s.