I've heard a single word before that means "withholding medicine from a sick person" or "withholding food from a starving person" or "refusing to alert an airplane pilot flying in the dark that he's about to crash into a mountain". The basic idea is not taking some action knowing that inaction will later lead to harm for another person.

I thought for sure there was a single word for this (and it's more malicious than "negligence"). What is it?