Killing a federal employee isn't necessarily a federal crime unless the act was committed "because" the person was a federal employee. Franklin's killing was random.
However, there may be other federal charges that can be filed. And, we could always send him to Gitmo given that I don't believe he is an American citizen and he did commit an act of terror against the nation.
OR ANOTHER VIRGINIA LOCALITY....STEP IN A.S.A.P. AND GET HIM TRIED FOR KILLING SOME OF THE OTHERS! AND SENTENCED TO THE APPROPRIATE FATE FOR A TERRORIST BY SOCIEITY... at least the cat is in jail and is not going anywhere for awhile.....