Cillaliz, why was he only charged with two counts of murder and three counts of attempted murder? Don't all the other people count?
Because this is the federal court case. Murder is generally a state crime. For the judge, the staffer who died, the staffers who were injured and the congresswoman it's federal because there is a statute that says it's a federal offense to kill, assault, etc a federal employee acting in their offical capacity. The complaint apparently states that Judge Roll went to talk to Congresswoman Giffords about the HUGE caseload in the District of Arizona. That's totally plausible since the caseload there is a huge issue and it would mean he was acting in his official capacity. The staffers and the Congresswoman were clearly doing an event= official capacity.
They have made it clear that there could be more charges. The murder charges for the others would be in state court as there is no federal jursidiction for them. It wouldn't be double jeopardy because the federal court is a separate sovereign from the state court so you can be tried in both courts for the same event.
They had to start someplace and it makes sense to start with the highest profile cases. If the evidence shows he was targeting Congresswoman Giffords, as is expected, then it would make even more sense to start in federal court. That doesn't mean it's the end of the charges, only the beginning