If you read the Kristen spoiler- she does not say the killer is shocking- just the manner in which the female victim is killed- that is what is shocking- the way it happens not who does it.I think like Boone's death it will be obvious. There's no way Jin or Claire will be the killer. It will have to be Ana-Lucia or Kate (or Rousseau if she's returning to the cast- but it seems doubtful).
Also the part about the person may turn out to be a monster- Kate has been shown to be really cold-blooded in the past- no one on the island knows about her past except Saywer knows she killed a man.
Ana-Lucia is not a likable character. It would be shocking if she killed Shannon, but not surprising by the violence she's shown so far.
However, there is supposed to be a "love-quadrangle" between Kate-Jack-Ana Lucia-Saywer that develops once they are all together.
Handcrafted by RollDdice 2005