The concept that certain laws of a country may have some limited application outside its geographical boundaries is called extra-territoriality. Only federal laws have extra-territoriality. Murder, rape, battery, and kidnapping, the offenses alleged by some to have been committed against Natalee Holloway, are in the vast majority of cases NOT federal offenses. They are subject to the jurisdiction of the states where they occurred, and they are tried and punished under state law. STATE LAWS HAVE NO EXTRA-TERRITORIAL APPLICATION except in those rare instances where some elements of the crime were committed within the boundaries of the state and other elements were committed abroad.
What are some examples of situations where federal laws have extra-territoriality? Some examples of such situations would include the following:
(1) terrorism, as strictly defined in law
(2) crimes committed by or against American citizens which occur on ships in international waters. This is how the FBI got jurisdiction of the disappearance of George Smith from the cruise ship in the Mediterranean. These cases can be prosecuted under what is known colloquially as the "Crimes on the High Seas Act."
(3) a crime takes place in a foreign country, but in a place where the U.S. has jurisdiction because according to international law the location is regarded just as if it were U.S. territory. Examples of this would include our embassies in foreign countries, as well as military bases. Shoot an American airman on the U.S. Air Force base in Vicenza, Italy, and you will be prosecuted according to U.S. law - either on the base or back in the States. Do it 20 miles away in the city of Padua, and you will be handed over to the Italian justice system.
(4) a crime takes place on an aircraft owned by a U.S. citizen or U.S. corporation while the plane is flying over international waters.
(5) a crime is committed against an American citizen who qualifies under international law as a "specially protected person." This usually means a diplomat. A regular, everyday U.S. citizen like you or me - or Natalee Holloway - would not qualify.
The list above is not all-inclusive. There are other situations where, in theory, federal laws MIGHT apply. In practice, however, it doesn't happen. The reason can be summed up in the Restatement (Third) of Foreign Relations Law (para. 432 cmt b (1986)). Note, in this case, "state" means the same thing as "nation":
It is universally recognized, as a corollary of state sovereignty, that officials of one state may not exercise their functions in the territory of another state without the latter's consent. Thus, while a state may take certain measures of nonjudicial enforcement against a person in another state . . ., its law enforcement officers cannot arrest him in another state, and can engage in criminal investigation in that state only with that state's consent.