I've slowly been playing through Torment anew on my tablet, and I decided I wanted to play as an evil character. I did the quest for Rauk in the Alley of Dangerous Angles, fetching him the three rings for his mage friends. After they summoned the killer Lim-Lim and perished, I provoked the Lim-Lim and killed it, which in turn made Rauk hostile, so I killed him too.
This apparently caused The Nameless One to go from True Neutral to Lawful Good.
I reloaded the autosave a few times to find out which exact trigger caused the alignment shift. It was not killing the Lim-Lim, but rather killing poor, innocent Rauk.
I've since been trying my damnedest to earn evil points, but having reached the Clerk's Ward, I'm still Lawful Good. Has anyone else experienced this?
EDIT: I've been able to consume 2 Tears of Salieru-Dei since killing Rauk, so it's not merely a display bug in the character sheet either.