unknown_murder_effect

unknown_murder_effect = {
	# Party Baron handling
	if = {
		limit = { $VICTIM$ = { has_character_flag = is_party_baron } }
		set_local_variable = {
			name = murdered_party_baron
			value = yes
		}
	}
	# If we're a clan this affects unity
	if = {
		limit = { # If the victim is landed
			$VICTIM$ = { is_landed = yes }
		}
		add_clan_unity_interaction_effect = {
			CHARACTER = $MURDERER$
			TARGET = $VICTIM$
			VALUE = minor_unity_loss
			DESC = clan_unity_murder_unknown.desc
			REVERSE_NON_HOUSE_TARGET = no
		}
	}
	else = { # For unlanded characters, we don't care as much, but you still lose some unity
		add_clan_unity_interaction_effect = {
			CHARACTER = $MURDERER$
			TARGET = $VICTIM$
			VALUE = miniscule_unity_loss
			DESC = clan_unity_murder_unknown.desc
			REVERSE_NON_HOUSE_TARGET = no
		}
	}
	$VICTIM$ = {
		#Killed by murder: set this up first to keep the killer hidden.
		hidden_effect = {
			death = {
				killer = $MURDERER$
				death_reason = $REASON$
			}
		}
		# Hide murderer in tooltip
		show_as_tooltip = {
			death = { death_reason = $REASON$ }
		}
	}
	$MURDERER$ = {
		if = {
			limit = { is_alive = yes }
			hidden_effect = {
				add_secret = {
					type = secret_murder
					target = $VICTIM$
				}
			}
			if = {
				limit = { exists = local_var:murdered_party_baron }
				random_secret = {
					type = secret_murder
					limit = {
						secret_target = $VICTIM$
					}
					set_variable = {
						name = murdered_party_baron
						value = yes
					}
				}
			}
		}
	}
}

As written in game/common/scripted_effects/00_murder_effects.txt.