Musical chairs in the State Box?

[L Verge]

I need Wes Harris to tell us about how far the gun shot residue would fly from a small gun like the derringer. Could it have reached Mary if she were within less than an arm's length of her husband (considering they had just been arm cuddling). It would seem that Booth would be closer to Lincoln than to Mary if he came from Door #7. Where is CSI or Bones when we need them?