While everyone is trying to pin this on Mossad, the main question is why would they commit their resources to such a relatively insignificant person? Mossad could just as easily have spirited him off somewhere. Unless of course he was in possession of... or perhaps other assasins from other groups with other interests were involved. Unlikely anyone but those who hit him will ever know for sure.
Syrian group says Nusra abducts its leader, in blow to U.S. plan (Reuters)
from the article: Ireland confirms 'Irish' Dubai killers don't exist