CBS Radio Mystery Theater - A Choice of Witnesses

On a warm day in early spring, Gordon Bailey is enjoying his workday lunch time sitting on a park bench.  A stranger walking by asks Gordon if he could sit with him. Gordon tells him to have a seat. They start a conversation in a friendly manner. Gordon says he works in the insurance business, and the stranger says that he is a photographer. Soon, Gordon starts back to his job, and the stranger says to wait just a minute, Mr. Bailey. Gordon says that he had not mentioned his name. How do you know me? The stranger introduced himself as Kellerman, and said that he knew him from the nametag he wore at the convention in Atlantic City last month. I have some very interesting pictures of you with a woman that is not your wife.