In the aftermath of Batman's staking, Killer Croc was among the many villains that took over Gotham City in his absence, beginning as a simple serial killer stalking the sewers before joining Two-Face's gang as the muscle.
When Batman was restored by Alfred Pennyworth, he embarked on a violent rampage, murdering and draining every major criminal on the streets and in Arkham Asylum until Two-Face's gang were the only villains left.
With no other choice, Alfred and Commissioner Gordon joined forces with Two-Face and Croc to stop Batman. Tracking Batman to the former Batcave, the group formed a plan to lure Batman out into the open and detonate explosives to expose him to the sunlight (although Croc briefly contemplated just physically tearing Batman apart himself before the others pointed out that he was too fast for him).
However, Batman was aware of the plan all along, and in the ensuing skirmish, he engaged in physical combat with Croc. Batman easily overpowered Croc and was about to bite him when Gordon shot him through the back with a crossbow. Outraged, Croc recovered and knocked Batman into a nearby chasm.
With Batman believed dead, Two-Face and Croc immediately turned on Alfred and Gordon. Croc took chase after Alfred, gleefully stating that what he was about to do to the old man might scare even him. However, while fleeing from Croc, Alfred came across Batman, still alive but severely weakened, and sacrificed his life and blood to give his old master the strength to save Gordon and complete his duty.
Still searching for Alfred, Croc came across his severed head, and looked up in time to hear the sound of wings. Rejuvenated, Batman broke a stalactite off of the cave's roof and impaled Croc through the chest with it, killing him instantly, before commenting that, thanks to Alfred's sacrifice satisfying his bloodlust for the moment, Croc could "keep his cold blood."