This is the result when discipline is outlawed and lazy parenting allows these feral children to do just as they like without a thought for anyone else or the the consequences.
It really doesn't take many like these nasty individuals to make people's lives an absolute misery. The problem is that even if they are caught, which is unlikely, nothing will be done about their behaviour, it will doubtless be put down to the poor situation at home, or some other pathetic excuse.
So sorry for the trouble you are having, and for the loss of your poor chooks, it must be heartbreaking.