RSBM
How does LE handle all of these jurisdictions as they did with the Golden State Killer when many states? Feds? So glad the FBI is sitting there in Rexburg still.
At least I assume they are still there as
@RexburgSleuth hasn't said they left yet.
JMO IANAL
For the moment, each of the crimes (alleged and suspected) seem to be fairly neatly contained in a specific state.
The current felony case (conspiracy to destroy, alter or conceal evidence) seems to fall squarely in Idaho. The (likely) murder charges themselves would fall in Idaho. Any murder case around TD would likewise seem to fall squarely in Idaho. The murder of CV falls squarely in AZ, as does the BB attempted shooting, and (if evidence surfaces to make it homicide) AxC's death.
If things stay neatly contained, the involved states (principally ID and AZ) each prosecute the crimes committed in their own states. I am not sure what the procedural rules are for that, but I would assume the states would negotiate for order of precedence (who gets them first), and I'd assume that Idaho would win that contest, since there's a trial process already in motion, and the murder of the children is the focus of tremendous national public attention and outrage.
If we look to Ted Bundy's case(s) for an (extreme) example, he was convicted for the murders he committed in Utah and then extradited to Colorado to stand trial for the murder(s) he committed there. Then, of course, he escaped and committed the Chi Omega sorority house murders in Florida, for which he was eventually tried, convicted, and executed (in Florida).
Although the FBI is helping with the investigation, it doesn't seem like the federal government would have jurisdiction for murder unless certain criteria are met, mostly dealing with murder of federal officials, or on federal property or in federal jurisdiction like on a ship.
However! There are a couple of scenarios where one or more of these murders could be considered federal crimes:
Murder by mail (
18 U.S.C. Section 1716) -- If, for instance (and I don't favor these theories) someone used the US Postal Service to send Alex Cox some toxic agent to cause his death, that would be a federal crime.
Murder for hire (18 U.S.C. Section 1958) -- "Use of interstate commerce facilities in the commission of murder-for-hire". If any of our band of misfits solicited anyone else to travel across state lines in the commission of (or conspiracy to commit) a murder, or used phone, email, or internet to conspire or facilitate murder, then that could be a federal crime.
It will be interesting to see how this all plays out as the investigation(s) unfold!
JMO IANAL