i was thinking killed in water... it would be odd to make the cut after death so thats not likely... oh and the idea about it raining is possible too i guess...
It really does appear that his throat was cut, and possibly more cut or stab wounds, then he was tossed off a bridge. His clothes, hair, and face still appear to be wet. Cabriolet.
If you look at the bottom of the last picture you can see he is obviously still in some kind of body of water at least up to his thighs...it looks to me as though he was just pulled from a lake or river etc