1) A polytheist prisoner must be killed. No amnesty may be granted to him, nor can he be ransomed.
2) All infidel polytheists and the People of the Book (i.e., Jews and Christians) are to be killed. They may not be granted amnesty, nor can they be ransomed.
3) Amnesty and ransom are the only two ways to deal with prisoners.
4) Amnesty and ransom are possible only after the killing of a large number of prisoners.
5) The Imam, or someone acting on his behalf, can choose between killing, amnesty, ransom or enslaving the prisoner.
Killing a Prisoner for the Sins of Others is Permissible.
source:
http://www.qoqaz.com/