Why not play the death sfx directly then kill_critter or DMG_NOANIMATE? It seems to me you don't really need the animation itself (don't see a point for map exit), only need the screaming.
play_sfx("HMXXXXBF");
critter_dmg(self_obj, 999, DMG_normal_dam bwor DMG_BYPASS_ARMOR bwor DMG_NOANIMATE);