Other than the last objective not really being clear in your destination, I had no troubles with Hakeev killing himself. He did the superman routine on me, too, but was on the ground at the end of the combat. I ended up dying after Hakeev, and had to find my way all the way back through the cat walks without the benefit of the guide
I had Hakeev and one of his guards jump up and off around the top of the buildings, followed right after by all the red shirts helping me. I was able to get hakeev down to a level where I could fight him again by backing off down the alley I'd come along to get to the plaza he was in.
I had the same issue. Wow, don't make us check the body if we can't get to the guy! We can't even jump over those dinky railings to try to walk the ledges over to him. Big time fail on that one, guys. This is a long mission I now have to do over, and try to keep the dummy from dying on a rooftop. Great.