The SAS like other specialist anti-guerilla forces are trained killers who have been conditioned in 'Killology" as a normal part of their training.
SAS candidates are selected from across the forces using a filter system where a touch of psychopath a sprinkle of authoritarianism seems to go a long way in qualifying.
The Milgram experiment is useful to check out because it seems to highlight the authoritarian type personality:
Add to that a bout of Pavlovian conditioning and there you have him....
