The thing is there IS a level of canon info we know from Blood in Baldur's Gate.
As the character is per definition an avatar, there is no real cannon if you play as DU. If you don't, you might encounter the said race.
That being said, I find it funny because I indeed plan to play as a dark urge wild magic sorcerer. But as a drow.
I think the said murderer was a wild mage as I did not see any scales of a different colour. And Larian does not seem to be that boring to pick both the race and the bloodline from the same colour. I could be wrong, of course.