I am not 100% sure about this but I understand that international laws would claim that even a terrorist has human rights and they should be arrested and brought before a court. They should not be killed in cold blood. This may not seem fair because the terrorists are known to kill hostages in cold blood, even to broadcast the killings on social media. And, while this is horrifyingly inconceivable and unconscionable, the right thing to do is to treat them as you treat any other human and give them due process.
There are very clear human rights laws for prisoners of war but the war on terror is not really a war, as defined by the Geneva Convention, so the human rights of terrorists are, unfortunately, a bit uncertain.