I've killed live 5 people already and none of them were High Profile. The only others I can think of are in the Jarls court, but they're all essential. Plus the people I've killed inside buildings and such don't seem to count. Who in Markarth, that isn't essential, could be considered High Profile?

Have you tried any vendors? Maybe the court blacksmith?

Was hoping I wouldn't have to kill the Court Smith since he makes entering Orc Strongholds super easy... Well, I'll go give it a shot.

Edit: Yeah, it's like I thought. Anyone inside a building won't work. I don't get a Quest update for killing them. Has to be someone outside, and Street Vendors don't seem High Profile.

Don't bother. You get the same stuff no matter what. Just kill a guard.

I killed Ogmund and he was considered high profile enough to fulfill the optional quest part

Street vendors count