History
The Starbrand Corps were sent by Uatu the Guardian in search of the "traitor" Hal Jordan. Hal wasn't guilty, but the real traitor (Uatu himself), killed each member of the Corps. When Uatu arrived on Earth, where Hal was, he was apparently killed by Speed Demon, who then killed Jordan because of he didn't want to repent of his past sins.[1]
Trivia
The Starbrand Corps could be a combination of the Green Lantern Corps and the Star Brand.