ยง 2. Crimes
Section 5
3. Anyone who commits, in the case of an international armed conflict, one of the following acts:
(e) killing or wounding a combatant who is in the power of the adverse party, who has clearly indicated he wishes to surrender, or who is unconscious or otherwise hors de combat as a result of wounds or sickness and is therefore unable to defend himself, provided that he refrains in all these cases from any hostile act and does not attempt to escape; or
shall be liable to life imprisonment or a term of imprisonment not exceeding thirty years or a sixth category fine.
Killing or wounding a combatant who has laid down his arms and surrendered at discretion - IAC
Killing or wounding a combatant who no longer has means of defence and has surrendered at discretion - IAC
EDIT.