(I'm not sure if this is a bug, as I'm not sure what happened, but it can't hurt to post it, this thread deserves a bump)
I have a special case for the Crime Scene Investigation squad:
This happened right after the elven trade caravan announced it was going to leave, I centered the viewscreen on the trade depot to be absolutely sure that the treehuggers were really packing their bags, and was just in time to see Alicirc Abiepicirorip, elven spearman, fall to his knees and die. (His graphic just changed from a living elf to a dead elf.) There was nobody in the direct neighbourhood except for his fellow elves, their animals and the wagons. Apparently he somehow bled to death as the square next to him contains a puddle of blood staining the white snow. After his death, the other elves just left as if nothing ever happened. The trade depot is near a magma pit, but there apparently was no smoke or fire involved. It apparently gets quite cold in winter at this location (it happened in winter, outside) but the area does thaw for a few months in summer. some of the other elves had some minor injuries to their throat and spine that I can't really explain (light grey)
This is all I can come up with for now, I still hope some dwarf will give us a clue by making an engraving about this event, but changes are that won't happen.
Now the death of this elf, does not really worry me, but it would be nice to know what happened. Maybe I could use it more efficiently against the next caravan.
Edit : I could backup the save, quit the fortress and check legends, will do that tomorrow.
Edit2 : Nothing in legends. guess stuff does not show up in legends untill you explore the fortress with an adventurer which would likely not result in many clues.