McKeon was defended by a group of volunteer lawyers from New York City, including his brother-in-law, Thomas P. Costello, Emile Zola Berman, and Howard Lester. along with Marine Corps attorneys Lieutenant Colonel Alaric W. Valentin, Major John R. DeBarr, and Lieutenant Collins. Berman led the team, as he was a distinguished and successful trial attorney who specialized in negligence cases, but he was also dedicated to preserving the constitutional rights of the criminally accused. He had previously presented a successful criminal defense in 1954 in Alexandria, Louisiana, of a 14-year-old African-American charged with rape and would later go on to defend Sirhan Sirhan.