Firstly my deepest condolences to all those concerned. This is a real tragedy and it's up to us all to make sure that nothing like this can happen again.
There is much talk about altitude separation, by various means over this incident. I was an Intercept Controller in the military until recently, not an ATCO' just a "Freddie". But I was thoroughly trained and examined in ATC procedures and separation techniques. I was taught from day one the correct way to separate aircraft is lateraly. A ten degree heading change when aircraft are 40 miles apart will give a lot of separation.
Leaving it to trying to achieve 1000ft separation with 50 secs to go to collision, late at night, with one aircraft from a country whose understanding of English might not be the best, flying an old airliner, is seriously reducing the odds.
Let us let the investigation take its course and have everyone learn from this tragic event.
God bless their souls, may they rest in peace.