Having been involved in such investigations....as the investigator thank goodness....the easy part of the affair will be in dealing with the DOD authorities.....now the FAA on the otherhand....that part of the affair can have its own life. The good news for the Swiss guy is.....if he can do a runner...the Swiss might refuse to extradite him back here for the toe nail pulling he can expect from the FAA.
The more interesting place he could have landed is at the USMC helicopter facility where the Prez's choppers reside. There the jurisdiction issue gets very convoluted....you have DOD level, USN, USAF, FBI, Secret Service, Park Service, and State Department (read that however you want) and some local cops involved. It all depends upon what he landed on...or taxied across....grass is usually Park Service, some roads are local or Federal, different portions of the airfield and ramps belong to all branches of the military.....my partner and I quietly slunk off to the government car and turned off the blue lights and headed for the nearest Dunkin' Dognuts shop leaving about a dozen folks arguing who had jurisdiction over one poor black guy who had gotten into a drunken fight with his girlfriend and then driven into a fence on the perimeter of HMS-1's turf. We reckoned there were more qualified investigators there.......plus we got a discount on the dognuts.....errr doughnuts.