Fang's killer...

So, when you finally find out who killed Fang, you will want to kill LeHavre.
To do so, you need an automatic shotgun (I used the Boar) and do the following: go to the merc that is to LeHavres' left, jump over him and enter the tiny room. Once there, peak around the wall and activate LeHavre. Go through the dialogue lines and they will become hostile. At that point, simply hide behind the wall and wait for them to come to you.

LeHavre is too far away for me to activate in that way. I simply kill both guards (no repercussions for me), initiate conversation and quickly move to the same little room when he becomes hostile.

Alternatively, you can toss 'nades from outside the building, killing LeHavre and take it from there...

I approach LeHavre with respect. I do so because I'm attending his funeral

I say a few words, then remove his two bodyguards from the scene. I respect them too, and want to spare them what comes next

I dispatch the mercs who come to his aid. They do so only for the money, and I have no respect for them

LeHavre, unaccustomed to this kind of work, decides between fight or flight, and chooses the latter

I give chase - but the Zone is my training ground, and I can keep this up all day

In his panic, LeHavre runs straight into a Vortex, and I watch respectfully as the Zone dispenses its anomalous justice

In his final seconds our eyes meet. I'm to be your last sight on Earth, LeHavre, and I'm thinking of Fang...