At least the idea of Freeza being dead is exclusive of Viz, but if it's not, then who was the one who killed him in everyone's mind?
There's also this:
Chapter: 328 (DBZ 134), P1.4-5, P2.1
Context: after learning that Goku beat Freeza
Tenshinhan: “B-but, to think that a Super Saiyan would be...