The problem here is that he was killed as a ghost. The story is as following:
Urist McMason was very smart. He always thought to himself:
-Why should I take a long road back to the Fortress, when I can save three tiles and walk over that frozen river! This is genius! Armok bless the ice.
However, when spring came and part of the ice in the south melted, that should have rang a bell to Urist McMason. Not only he refused to clean himself from well within a fortress(platinum block, platinum chains, platinum bucket, and engravings around the well), but he insisted on walking down the ice north of the river to save himself three extra tiles of walk.
-How can they clean themselves inside the Fort? Look at all the sunshine, flowers blooming, birds singing. This is what..,-suddenly Urist McMason heared a cracking noise, that made him stop his monologue, - What is that noise? Why is it coming from the ice. AHHH, Bulb-bulb-bulb!
Urist McMason was a good mason but horrible swimmer. His body has not been retrieved from the river. For six month, any dwarf that would pass by the river would see two pale eyes and a smile, looking at them from the sand bottom. Then, in the late autumn, ice covered the river again, and since then noone could find Urist McMason's body. But they say, if at night on the full moon you look at the river, then you might see a ghostly dwarf walking and cleaning himself in the river.
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Well, I am not good in writing anyway. But you get the concept on his death. After two or three years, he came back as a ghost. I did not mind him. He was neutral. Would not do anything bad, except haunting some other dwarves. Once after an ambush I looked through one of my dwarves kill-list to check his contribution. That is when I saw the killed ghost. So I looked over the battle report and there it was. There were fighting for unkown reason but then ghost got strucked down. I looked for the ghost of "Goldenbridges" and did not find him anywhere. So I assume he got vanished into oblivion forever.