I have put this under a spoiler button, as it is for DMs only.
Spoiler:
On page 61 of the adventure it says: "She [Red Shroud] informs the PCs that the tooth [of Ahazu] was recently sold to a varrangoin outcast named Sutolore". Actually it is the other way round in the sidebar in Sea Wyvern's Wake: Sutolore tries to sell the tooth to a lilitu demon agent of Malcanthet in Broken Reach, and thus it comes to the attention of Malcanthet, who then recruits Sutolore to put the item in the cave of Zotzilaha and take the bat statue away with him to Tamoachan. Just so that you know and can avoid awkward PC questions.
Spoiler:
I presumed this was Red, who works for Malcanthet, deliberately obscuring her mistress's intentions to the group. They wouldnt know about the truth unless they interrogated Sutolore, and he's a demon, he could have been lying.
The question is which demon are they going to trust... the one they killed wya back when, more likely than not, or the one they need to be on good diplomatic terms with now?
Spoiler:
I have players who always seem to spot such things. If not by negotiation, then in other ways. Three of them maintain a campaign diary with lots and lots of notes. I seem to remember they intimidated Sutolore with quite a high score, so he did not even dare to lie.