jsidhu762: BG 1 & 2: The Sword Coast has a child killer epidemic
NotJabba: Isn't it just the same guy in both games? Or maybe there are others I'm forgetting.
Child killers in...
Baldur's Gate 1:
Neb - A serial killer who resides in prison. He disturbingly know how to escape the prison easily.
The Talonites - They are close to the bridge to Baldur's Gate and were conspiring to murder a 12 year old girl
Ankhegs - A farmer by the entrance to Baldur's Gate will ask you to retrieve his son. His son was killed by ankhegs and you are charged with bringing his body back to the father.
The spider quest - On your way to Cloakwood, a young man by a waterfall will ask you to help rescue his brother. Turns out his brother is actually dead and you have to bring his body back to finish the quest.
Durlag - Went insane and murdered his family. I think it's suggested that the dopplegangers killed his kids before Durlag went mad.
Church of Umberlee - A priest's son was playing near a church of Umberlee and wandered in by accident. The child was killed for trespassing. Another quest where you have to recover a dead child's body.
Baldur's Gate 2:
Neb - Makes a cameo. If I remember correctly the quest that leads to fighting him is given to you by the church of Helm after the unseeing eye quest.
Slavers - If or when you lay siege to the slaver compound in the slums district in Athkatla, you are able to rescue several children. It's probable that these aren't the first or last kids to be kidnapped for labour. Any child captured this way will either be killed by dangerous conditions, or die trying to escape their captors.
Jan's relative - If Jan sticks around long enough in your party, you will eventually get a quest where you have to go to his house in the slums district. There's a girl (I forgot how she's related to Jan) with an illness in her brain. If you don't recruit Jan to finish the quest it's probable the girl will perish. Edit: I forgot to mention that the illness itself is unnatural.
Paladin at the graveyard - A paladin in the graveyard district mourns his son whom he unfortunately wasn't able to save.
Little Man - In the graveyard district at night the ghost of a gnome boy will approach you and ask for his teddy bear named Little Man. He was killed by a dwarven burglar and the villain can be found in the Copper Coronet in the backrooms.
ToB - Various Bhaalspawn have acquired wealth, power, and armies and attempt to achieve godhood through megadeath. Saradush and all of it's civilians are eventually slaughtered. The Bhaalspawn conflict isn't limited to this area and it's safe to assume that various hamlets, villages, and towns are eventually razed.
Those are the ones I can remember.