I missed it the first time around. You're right -- there's an eerie silence surrounding this story. There was no mention of it on Yahoo news, which is really odd. Remember the Kelly story? It was huge when it first came out. Similar, and strangely quiet.
However, when I entered 'John Kokal' on Yahoo search, I got 1,340 web sites covering this story. So there is information out there.
Now Mr. Kokal was evidently involved in some Iraq intelligence gathering, so he could very well have been killed over some information that he had, and they didn't want it to get out. Or, he could have been threatening to go public with some information. In that case, there may have been some previous statements where he had spoken out, or divulged some information publicly. In other words, if he was "going public" he probably did so at some point before he was killed.
My hunch? I think he was killed to send a message to EVERYONE at the State Department as well as the CIA. Karl Rove and the White House wants to make it very clear that if you go against them, you are in mortal danger. Kokal could very well have been a "company man", but was useful in this "demonstration".
However, what's even more shocking are the sheer numbers of people who have been either kicked out or have resigned since this murderous administration set up shop.
This website goes into more detail and covers the death of John Kokal:
http://www.missouri.edu/~quinnl/news/bodies.html