Chapter II
Crimes
Section II
War crimes
Article 10
War crimes against persons
1. Anyone who, in the context of an international armed conflict or a non-international armed conflict, commits any of the following acts against a person protected by international humanitarian law:
(e) Killing or wounding a combatant who has laid down his or her arms or who, no longer having any means of defence, has surrendered unconditionally or has been placed hors de combat by any cause;
shall be punished with a term of imprisonment of 10 to 25 years.
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.