This case bums me out so much, so much mystery! From my perspective only one who has dehumanized the family could have done this. I am not sure how effective training is for dehumanizing little girls. But what certainly is effective is hate (racism, religious judgement). A semi-pro murder of a wealthy Iranian family with a WW2 era german pistol (it might be Swiss issued, but I bet it looks just like the one the Nazis used) just reeks of hate crime.

I really love all the intriguing stories around it, but they just stem from the fact that beautiful/successful/rich people have interesting things happen to them. It's like red herrings in a British detective show.

If I had to be a rational serious detective on this case I'd certainly be looking for a Nazi gun nut with a good shot and social issues either locally or one that could've met the family somewhere along their trip.