Who killed Stefano Dimera on Days of Our Lives?

No one killed Stefano Dimera. He is alive and well. Everyone thought he had been shot and killed, but it turns out that Ian McAlister had kidnapped Stefano and faked his death. For awhile, everyone thought that Stefano's son EJ had killed him. However, all was revealed in August 2012. Ian was caught, and Stefano was found unharmed.