Laerta and Louise

Twin girls Laerta and Louise say they are being stalked by a 'bogeyman' at night. They can be found in their large house located in the district of Northwest Baldur's Gate.
After speaking with Laerta, two suspects will reveal themselves: Voltine and Gervisse, and Gorion's Ward must deduce which is the culprit. One way to do this is by finding out which one of them is evil (Detect Evil or Know Alignment spell). The quest entries in the journal also give clear hints on who to trust — after talking to Gervisse the entry ends with: "There is still something that disturbs me about all of this, but I'm not sure what..." — but after talking to Voltine the entry ends with: "While I got off to a bad start with Voltine, I sense she is the one telling the truth."
The party needs to kill the culprit: Voltine is worth 60XP, Gervisse 900XP and Voltine will give the party a Wand of Polymorphing as a bonus if they kill Gervisse instead of her. Once this is done Laerta must be talked to again to complete the quest for 1000XP and a Protection From Evil scroll.