Hi all, how can I recognize in a quest if an npc is died or not (to make various conditions)? Thanks.

YourActorACHR.http://www.creationkit.com/IsDead_-_Actor

Doesn't work in quest stages fragments and I can't fin it in the list of conditions of conversations.

Try writing a script, attaching it to the quest (not a fragment) and create a quest stage to use when the actor is dead. When IsDead returns true (or, better, use an http://www.creationkit.com/OnDeath_-_Actor event) to trigger a SetStage to the new quest stage that happens only when the NPC has died. Hopefully that will work. (My papyrus-fu is not strong yet)