ADAM: All signs point to very soon. The show has begun looking for an actor to play the three-episode role of an elite sniper who is suspected in the assassination of an important character. This particular suspect is an ex-Army sharpshooter who left his previous post in disgrace after being a little too trigger-happy during a hostage situation. He has been hiding under the names of other famous snipers, including Booth's, which is ultimately what leads the FBI straight to him. Well, that and the fact that he's the only person besides Booth who could make such an impossible kill shot.
Source: TV Guide
Tipster: jessica_sj08