I guess I'll finally voice my opinion on this,
...instead of poking fun at some of it.
I'm of the opinion that the party willfully commited an evil act, with the result being the death of their hostage.
A member of their group, known to get a buzz from stealing, was caught by the local law. They were within their rights for arresting said member, although we do not know the details of the local government and laws, as well as whether or not it's a Lawful/Neutral/Chaotic society, etc.
The group decides to kidnap the daughter, my inference is that she is a child (or minor), instead of staging a prison break, or bribing an official. Why? Who knows, their choices (do they need the thief that badly? owe them in some way? loyalty?)
The child, obviously in fear of being taken by these strangers, tries to call for help. A party member's response? Hitting her in the head, hard enough that it kills her. Other options? Lots, including gagging her with cloth, etc. Did they do it? Nope.
I don't know about you, but has anyone seen the movie 'Ransom' with Mel Gibson? I don't know about you, but I felt all the kidnappers, even the dumb-one, were being evil in one form or the next.
You steal a youth from her home, so as to black mail her father into releasing their friend and accidentially kill her when trying to gain her silence.
Blunt force was used, from the edge of a sword, and she died. No spells. No gags. Minor restraints.
I'm sorry, but I don't need motives to know the act was evil. Hell, depending on the society it could even be considered Lawful Evil - remember, it's evil within the constructs of a society's structure.
The party had options, but they took the easy route and really screwed the pooch.
It might not be full blown, Lolth is coming over for tea, evil, but it was an evil act.
Within the constructs of the game it was evil, it's pretty evident. Kinda like how certain spells have - [Evil] - next to their names.
Personally, if the group is smart, they should run like crazy. Leave behind their friend, hope no connection is made, and just run.
Those of a divine nature, with a Lawful or Good diety are pretty much going to be introuble, but that's just my opinion.
Just tonight my Lawful Neutral Wizard fired a ten-foot wide by one-hundred foot long lightning bolt into a wall of barrier shields - he was forty feet from the shield, it blasted right through it and killed the seven orc warriors holding the shields. It also killed the women and children. They might be orcs and it might be justified and it might be excusible since he could not see them, but he still feels guilty about it, as he considers it evil.
He'll be making a lot of prays to Mystra, but his life will go on - hopefully the same can be said for the party too, from this thread.