If you look at the picture in the link, you'll see that there is a small flat roof just outside the window on the top floor. If the argument moved out on to there it is quite possible that the first physical contact was a good hard shove that sent him off the roof. Again, all this is conjecture, but it is possible that nothing but a shove took place.
Absolutely have the right not to incriminate yourself.
El Tejon - nico has already given a scenario where an American can find themselves in deep doo doo with a burglar. Like I say, if it looks like an execution, do you really think that there isn't going to be some effort at investigating exactly what happened?
