Can you tell where it took off or landed? Looking up airport tenants might be very informative. If we had a tail number we might know which agency it belongs to. If anyone has a photo showing its livery that would also be helpful. The FBI is known to use Cessna 208 planes for surveillance. An example is N956D leased through a front company. I suspect this is the FBI hiring a local FBO to fly them around. You can look up tail numbers here:
Aircraft Inquiry
It seems highly likely this was an FBI surveillance plane.
Incidentally, the JPATS aircraft fly under their own name so it is quite easy to find them. So much for security. Think how many reporters are watching Flightradar for a JPATS plane heading to western Idaho! We don't know he'll be on a JPATS plane but the alternatives are private jets and commercial flights. A commercial flight would not surprise me but a private jet would be similarly easy to track.
LE can NEVER turn off their transponders in civilian airspace. This would be a HUGE air safety risk. Even the military is required to squawk in most areas outside of military airspace. Even Air Force One identifies itself!