Michael Selby (later Shelby) was an independently wealthy private eye who became the first Green Mask to fight injustice. He was non-powered, using only his wits and firearms, until he was mortally wounded while trying to protect his father, an influential senator. Senator Shelby sponsored the passage of the bill that would make death sentences mandatory for all gang members, which was why a criminal organization known as the Grim Circle had him assassinated. To save Micheal's life, Professor Lascomb, a friend of the senator, exposed him to vita-rays. Because the machine was overloaded, Michael not only recovered, but he also gained super-strength, super-speed, flight, and limited invulnerability.