I saw a special on the History channel about this. They said 3 guys did it, and were captured and spending time in jail in another country. They said it was a Mexican hit crew. An American regime change, if you will.
American leaders were afraid of getting into a war with Mexico, so they let the Oswald story take the headlines.
Like the ME connection to the OKC bombing. Clinton found it easier to blame just 2 men, and let the real story slide. Otherwise, Clinton would have to be presidential - something Democrat politicians fear.