Liked the movie, is this based on anything legit?

This has been showing on Showtime lately and I've always been a sucker for conspiracy movies and this topic in particular even though I wasn't born until after the assasination. When I read the info I had to DVR it and I enjoyed the movie. It's movies like this that deliver value for my Showtime subscription as I never heard of it and wouldn't find it in Redbox or notice it at Blockbuster.

I'm curious if this movie was inspired by a real theory or situation?

Of course, I'm not THAT curious because I don't wish to have an unfortunate accident anytime soon.

Now that I think about it, a lone nut killed the President...oh well? That sucks, happened a long time ago so I'm going to live a long, peaceful life now.

Noah