Oh, this is a classic US thing to do!
Remember the death of Harry Dunn:
https://en.wikipedia.org/wiki/Death_of_Harry_Dunn
There are plenty of other stories of the US helping their service members and families avoid local justice.
I am not that pissed about the service members, because the US and the host country of their foreign bases usually have a deal where the service member can't stand trial in the country and that they will handle their own punishments in the service.
However, to my knowledge, this doesn't extend to dependents.
Which is why the above case pisses me off way more than other cases involving service members.
In general I think it is a decent agreement that the nation to which a service member belongs to takes the responsibility of maintaining discipline among their ranks, but the punishments dealt out by the nation tend to be rather mild, and seem to forget that the service member is representing the nation in the host country, and their behavior is detrimental to the nations interests, and thus should have a harsher punishment.