Okay I am writing a story where an FBI agent is implicated via ballistic evidence in three murders. Two of the murders were with weapons that were supposed to have been turned in for destruction due to age and use (he's a sniper). One weapon is supposedly his currently issued weapon.
Now of course no one working the case actually believes he did the murders. So right now they are 'holding' him pending clearing up the weird ballistics match.
The problem is the case crosses a DHS case involving a known terrorist said FBI agent knows and once trained. Now he does have an alibi for the murder matched with his current rifle. There will be three more murders matched to those rifles. And a mountain of circumstantial evidence against him, i.e. he will have been in the area at the times of the murders but for reasons he does not want to disclose.
The DHS agent will arrest him. At what point would she make the arrest?
The murders take place in several different states, where would the trial take place, in the city where he is arrested?
What would happen in terms of his job?