i can't understand how i died

@xeoxxmin Nasty six and EA Cuervo did a good job answering your question, but I just wanted to add this complex you were at on Olympus is one of my least favorite places because it is very easy for someone to pick you off from the top floors like they did you. It happened to me many times, and when they do gun run there it seems 10x harder to me. I too have gotten multiple kills at this location only to have someone I didn't know was there shoot me from the 2nd floor of another building, so I try to not drop there and to be careful if passing through.

I think that's why this is the one location where it can "seem" like a cheater killed you, but it's actually because of how the buildings are laid out.