This may have been a feature of Persian religion, but I've never come across it in Sumerian or Babylonian religion, explicitly or implicitly. Enuma Elish postdates Hammurabi by a millennium. If Tiamat had a cult anywhere, AFAIK no record of it has been found. I'm not aware of any other god said to have been killed by Marduk - rather, the rest of the pantheon elect him as their leader.