In this AU, Petey is completely psychopathic villain who has committed several crimes, including making an attempt on the lives of several people with his experiments.
The explosion towards officer Knight was an event which for Dogman completely marked him, because he was able to witness before his own eyes the death of his former owner.
Dogman has to capture Petey, however, that trauma is still present and it is difficult for him to catch the cat responsible for the officer's death.