1 - Put playable AI unit (named p1) on editor.
2 - on description.ext set:
respawn = 2;
respawnDelay = 2;
respawnDialog = 0;
respawnButton = 0;
enableDebugConsole = 2;.
3 - Play mission
4 - Get in debug console and type:
p1 setHit ["head",0.6];
you can see the blood on his head.
5 - kill the unit.
6 - repeat step 4.
the blood on the head not appear any more.