I think it's possible some JWs are trying to prepare themselves mentally to do almost anything in service of their god.
I also think it's possible murders could take place on a larger scale under the right conditions. For example, say there is a war on US soil (because JWs place so much more biblical emphasis on what happens in the US)....things get chaotic, ppl go into survival mode...a few higher ups in the Borg say JWs should be helping Jah in his campaign to exterminate unbelievers....rumors fly but formal communication methods break down....food supply diminishes, ppl fear for their personal safety.....the only way to get enough food for your family is to steal or kill off others who have food....I can envision some JWs taking on the task of killing....justifying it by saying Jah wanted their family to live and the "wordly" family is going to die anyway....but surely not all JWs would do this.