I killed a Druid during the fight where they tried to smoke out the Tieflings.
So Tieflings saw me kill "a Guard" (Druid) during the fight.
A DRUID THAT TRIED TO KILL THEM.

One of them shouted
" Oh my gods the killed a Guard. Quick, alert everyone! " or something. ^^
It gets even better ... i experienced the same when i attacked groove with goblins, but one of my goblins was withness of my murdering spree, and go alert guards ... yet he probably didnt find any, since he become hostile himself a few rounds later ... then, when other goblins killed him, Minthara become hostile to me since "i spilled some blood".