Denny Goodwin may once have been mild-mannered. But if so, that died along with his innocence when he started covering the crime beat. Seeing the underbelly of human civilization, all the evil that men do, has a way of changing a person.
He was covering a series of horrific killings and mass suicides when his powers emerged. He discovered that he could perceive connections between events in the papers, understanding links that would otherwise have gone unnoticed, and he developed a symbiotic relationship with the city itself. These traits allowed him to go outside the limits of law enforcement, tracking down criminals wherever they hid and subjecting them to vigilante justice.
As The Crime Blotter, clad in a costume that looked like it was made from newspapers, he used his powers to track down and capture Daddy-O -- the cult leader and serial killer responsible for those atrocities.
The Crime Blotter continues to cover crime in the guise of Denny Goodwin, even as he punishes it as the scourge of the underworld by night.