Tad Cummins is currently in Federal custody, facing Federal charges. He will be returned to TN to face said charges. The states of TN, & possibly CA may also decide to press charges against him.
I think (but may be wrong), that Federal takes precedence over state - for the moment, but he could be simultaneously indicted on state charges.
ETA: https://www.google.ca/amp/whnt.com/...appears-in-federal-court-for-arraignment/amp/
N.B.: I'm not entirely sure that Siskiyou county has charged him yet (as reported in the link), but I believe they are considering doing so (can't find that link right now)
Thank you for the explanation. I am glad he will be charged twice.