Two years later, in The Avengers Annual #6 (November 1976), writer Gerry Conway retconned the character to be a mutant whose abilities were activated by the mongoose blood transfusion.

After the mobster Granno frames him and his father Emil for murder, they flee to Africa, where Robert develops a fever.

[7][8][9] After developing superhuman speed from the transfusion and defeating Granno, Frank then decides to fight crime and eventually accepts the offer of Invaders member Bucky, who forms the superhero team the Liberty Legion to rescue the other Invaders from the Red Skull.

[10] When the Liberty Legion and Invaders disband after World War II, the Whizzer joins the All-Winners Squad.

[11][12] The Whizzer afterward spent some years battling alcoholism and depression and was, for some time, homeless in the Bowery section of Manhattan.

The Whizzer dies after suffering a fatal heart attack while fighting Isbisa, but his sacrifice enables Nuklo to be cured of his excessive radiation and begin a normal life.

The Whizzer has learned a unique, self-taught fighting style that exploits the ability to move at superhuman speeds.