[elcapitan]

To be complete there: They didn't use gas from a tap, they used Cyclon-B, a cyanice pesticide which comes in cans, which is solid and becomes a gas when it gets in contact with air. They put it in from the top through the ceiling.

I think beginning with that point all the killing and removal work had to be done by groups of prisoners.

As for drones: Yes, there was an interesting keynote talk at 33c3 by a former us army guy who has become a whistleblower. They hire specifically for gamers to become drone pilots, because they already have that abstraction from their games. They see the bad guys (arabic looking people) on their screen and have less issues to hit the trigger than a pilot who would be based in the area.