After his death, he is mated with the Wrath of Vengence, The Spectre. He attempts to change the Spectre into becoming the Spirit of Redemption. Like converting a Republican into a Democrat. Well that didn't stick.
The Spectre was attacked and possessed .. by .. (wait for it..) .. Parallax. Yes, Parallax, a being that fed on fear. It turns out Hal Jordan wasn't sane when he murdered the Green Lantern Corps. He was being influenced by a creature of fear.
Under this nasty little fellows influence and moniker, Hal Jordan, Green Lantern murdered friends, colleagues and enemies. All his ex-allies and ex-friends saw him as a rogue hero gone mad. Our story however does not end here, not when there's more bucks to be made.
Parallax eventually succeeds in taking over the Spectre for a while. However, the Spectre fights off Parallax and frees Jordan from fear's grip. With Jordan freed, the Spectre leaves seeking a new, more compatible host.
The battle however did take its toll on Jordan. About to die, Jordan was guided by his old mentors (the Guardians) back to his preserved body to reanimate it. Alive again Jordan finds out that it was Sinestro (his old nemesis) who had helped to free the Parallax creature and manipulated Jordan.
Jordan resumes his role as Green Lantern in a fight against Sinestro and Parallax. With a victory over these two, he grandly reenters his comic book.