There is an angle to this story that probably would have bothered the hell out of me at the time, though. From what I've read, Stethem was apparently on active duty and was traveling back to the U.S. on leave or for re-assignment. It would seem to me that having active soldiers flying on commercial airlines like this -- particularly through an airport in Athens that was notorious for its lax airline security -- would represent a serious risk. Was this point even discussed at the time?
We do, as do most nations, based on the principle of passive personality as it exists in international law. The FBI often investigates crimes against Americans overseas, and offers rewards of information in all cases except Americans murdered in Israel. Generally prosecution is limited to cases where local officials refuse to act, but our jurisdiction isn't limited in that way. If we want to prosecute this murder, we can. We can and occasionally do also prosecute crimes of American citizens committed overseas. I believe this is becoming an issue in internet law.
Understand your point but you are wrong in this instance. 18 USC 32 makes it a federal offense to hijack an aircraft wherever the hijacking may occur. And if a death occurs, the crime is subject to the death penalty. 18 USC 34. Jurisdiction is based on the old common law theory of "universal jurisdiction that was applicable to pirates.
I understand the points you and Michael are making about the German justice system, and you have more grounds than us to be outraged since it is your system (I would be furious if a murder here was out in 15), but in this case they should have honored the extradition request rather than taken over a case which, as you acknowledge, they had no real connection to.
Also, active duty personal flying on commercial flights is a fairly common practice.