who was the guy...spoiler

Princess Diana's driver.

I just took him for a random prior victim that was still alive.

I wondered about that too. He was very evil and sadistic so this guy was probably just a random guy he enjoyed holding hostage, semi starving and beating (he was bloody). The other three posed a threat as he could potentially be connected to them (Toby, his mother and Omid) so he killed them. Plus, it was probably too much work to keep them alive as well.

It would have been nice if they would have explained who he was. I felt this was the one flaw in the film but I'm pretty sure he was just a poor, random soul. Aside from this one flaw, I thought this movie was absolutely fantastic!!

Just to add to my previous comment, I found this on line: "It seems Hector now kidnaps men and holds them hostage in some sort of revenge plan for what Ravi did to his family."

So it is just a poor, random soul who, in Hector's sick mind, possibly reminds him of Ravi.