Tonight's the night.
Finally I'll continue this after a long break. I hope Bernd'll forgive.
Previously I wrote about two of the killing enabling factors: Demands of Authority and Group Absolution. Today comes (after I bring a mug of tea and maybe a bite to eat):

Physical Distance.

It's kinda self explanatory. The farther the victim the easier the kill. It is already known for a while now.
''It has long been understood that there is a direct relation-
ship between the empathic and physical proximity of the victim,
and the resultant difficulty and trauma of the kill.''
The farthest distance is when the killer doesn't even see his victims. It's a totally ''impersonal act of war in which specific deaths are
unintended and almost accidental in nature''. Rarely a regret there. The closest distance couldn't be more personal. Killing the victim with bare hands feeling his/her skin, organs, even maybe breath. Seeing the victim's face as the life slips away. And remember it forever.

A quick rundown:
Maximum Range: "They Can Pretend They Are Not Killing Human Beings"
Long Range: " Not Eyeball to Eyeball with the Sweat and the Emotions of Combat"
Midrange: Denial Based "on the Thinnest of Evidence"