The Warren Commission´s conclusion of LHO acting alone should be taken with a BIG grain of salt. Mostly because the Commission investigators actually had not access to all of the evidence. Much of it was kept away from them. In the late 1970s the United States House of Representatives Select Committee on Assassinations (HSCA) concluded that Kennedy was very likely assassinated as a result of a conspiracy. But HSCA never named the conspirators.

Here is a link to a site which is a must read if you find the JFK assassination interesting:

http://www.jfk-info.com/files.htm