Steve,
Would that law (1963) have been legislated to account for Washington DC which is not a State but is a separate part of the USA?
Military installations could also be subject to Federal Law not State's.
Was there any evidence (not speculation) discovered between November 22 - 24 November 1963 that would prove Lee Harvey Oswald conspired with a person or group to murder John F. Kennedy?
Ross, this is above my pay grade <g>. I guess probably not if it had taken place on city/local property such as a DC street and not on Federal property (the attempt on Truman was done in the Blair House, which was federal property; so the attempted assassins were prosecuted under Federal law).
DC has an odd judicial system (I lived in Northern Virginia in the 1980s; not that that makes me an expert on this). The US District Attorney also prosecutes violations of city/locals laws. And the Federal courts in DC (judges are selected by the President) also hears violations of local laws. So if an assassin had shot JFK on the streets of DC I'll guess that the US DA for Washington would have prosecuted him for a violation of city laws against murder.
As to the conspiracy evidence on 11/24: None that I know of. Remember the controversy though about Oswald being charged as part of an "International Communist Conspiracy"? Bill Alexander, the assistant DA to Wade, said he told a reporter that but that he was just being provocative. But the White House took it serious and asked Wade about it. He said he didn't know anything about it since there was no Texas law against "International Communist Conspiracy"; just conspiracies.
Shorter me: I'm not sure about any of this <g>.