Nightwing stopped masked goons from trashing Haven in the last issue, and he was able to unmask several of them and his mask took records of everything. He passed the data to Oracle and she basically cracked the case and found their identities. On a press release by the Bludhaven police commissioner where he blamed the attacks on the public being helped by Haven, Dick Grayson and Barbara Gordon turned the tables by releasing the matched identities to news networks, proving that the masked assailants were in fact members of the Bludhaven police department.
From – Nightwing Vol. 4 #93