User blog comment:Seieireppa/God Eater:Universitas, chapter 46: No Other Choice, part 2/@comment-10225593-20150812012401/@comment-1419424-20150812013250

I mean, if his head was completely crushed or he got shot in the head, that's all it would take... well, that or the complete disintegration of his body, but destroying the head would be easier. Some brain function needs to remain in order for the ability to trigger, i.e. there still needs to be life functions still in place for it to work. If he was instakilled, that'd be it (unless Blake or Jack stepped in).