Detective Comics, Vol. 1 #776 (2002)

Orphan / Spore, Part 1
Members of Johnny Gilmore's gang are dying. The hits look like they were made by rival gangs, but Batman suspects that a policeman, formerly undercover, has gone rogue looking for some payback. Now he hunts for the former-cop before Gilmore's hoods can find him.
Release Date: 2002