[Nakota]

"There used to be a tv show called I Led 3 Lives. It was about a US agent who'd infiltrated a Communist cell operating in America. It was based on a real man's experiences (and his book)." I watched that too but thought it aired in the late 50's. The main caracture was "Herb Philbrick".

[weegee]

I see you are correct:

http://www.imdb.com/title/tt0045397/usercomments

1953-1956. And it was in color.