If an American citizen murders another American citizen abroad in a country which an extradition treaty exists, but is first arrested back in the United States where they have since returned to - where does the prosecution occur?
Specifically I ask the question because this happens in the fictional HBO show Search Party. After committing murder in Canada and returning home, the defendants are tried in U.S. court. I'm wondering if this is what would actually happen in real life.
18 U.S. Code § 1119 - "Foreign murder of United States nationals" seems to cover this topic but from my limited understanding it seems to imply that since the U.S. and Canada have a treaty the defendant(s) would be extradited to Canada for trial.
Aside from this it also states:
"...the Attorney General, in consultation with the Secretary of State, determines that the conduct took place in a country in which the person is no longer present"
and I'm wondering what that process actually looks like. Does the Attorney General have to petition the other government for permission to prosecute them in the home country? Does it make a difference if the key witnesses are also all Americans, therefore arguing that chances of conviction are more likely if tried within the U.S. where all participants reside and are available to testify?
Either way - does anyone know any famous/well known examples of this happening? I assume it must be well precedented in U.S. border regions.
Sorry if this question is woefully unaware, that's why I'm seeking out expertise.