The four "C" device was described to me as the symbol of the Serbian Chetniks. The C's stood for the first letter of a four word sentence that translated roughly to "Only Unity Saves the Serbs" or something similar.
The Chetniks were the force most beileved to be behind the Ethnic Cleansing for the Serbs in Bosnia (and likely Kosovo). The four C cross would be painted on the door of the Serb houses usually just before the Chetniks came in the night to "cleanse" the town. It now litters every manner of flat, paintable surface in Bosnia (at least, in the Serb areas).
The "Ustache" dealt with it for the Croats. They used a capital "U" as a symbol and are related in policy to the the German occupation of WWII (which was supported by the Croats). It was the Ustache flag that flew over the detention camps in Yugoslavia.
I recall it was most likely the "Black Swans" who did the ethnic cleansing for the Muslims, but they were more of a particularly effective commando group that consisted of men and boys who had no one else (orphans, widowers). They had a particularly strong burning hatred for Serbs. The "Swans" were their new family. I do not recall their symbol (the badge was a black swan, but I don't recall what they used to mark muslim locations..probably a cresent moon).
FWIW, I have done three operational tours though there, one UN, two NATO and had to endure Cultural Awaareness Training everytime.
