Question: What is the Islamic law regarding the prisoners which are caught in war? There are instances when Generals and senior army officers may be caught. There may be those among them who are guilty of genocide and other war crimes. Can they be put to death if they are captured in war?
    Answer:  According to the Qur’an, prisoners of war of an enemy with which peace has been concluded must be treated generously and set free at all costs – whether after accepting ransom or whether as a favour by just setting them free:

So, when you meet those who disbelieve [in the battlefield], strike off their heads. Then when you have shed their 
blood fully, bind them [as captives]. Thereafter, free them as a favour or free them with ransom till war lays down its weapons. (47:4)

    Although these verses were revealed for the Ismaelites of the Prophet’s times, yet they present an eternal directive regarding prisoners of war.
    Those among the prisoners who are guilty of war crimes must be given a fair trial and given any punishment on the basis of a court verdict. Without any such sanction, a state has no authority even to punish them let alone execute them.