Since they are not prisoners of war, the Geneva convention would not apply to them, even if Afghanistan were a signatory to Geneva.
Thank you. To counter their own claims: "the killing of captured prisoners in the context of an international conflict is a war crime,"
Afghanistan is no longer an international conflict. They have an established independent government that rules their country, and these AQ fighters are either treasonous rebels or foreign criminals. Since Afghanistan is a Muslim country, these criminals and rebels get to enjoy the fruits of Muslim law...including summary beheadings.