There was no Jabberwocky killer.
John Hatter (Gary Hudson) got into a fight with Alice Lurie (Loren Peterson) accidentally pushed her down some stairs apparently killing her. Hatter went to Margaret Ellison (Eve Crawford), who owned the house and she got rid of the body with her brother. However, Alice was still alive so Margaret killed her.
As for the other "Jabberwocky" victims they were unrelated crimes, whose crime scenes were tampered with to give the appearance of serial killer. Hatter hadn't killed anyone until he killed Harvey (Henry Czerny), a psychic who figured out there was no serial killer. When Hatter tries to kill Dr. Vera Swann (Polly Walker), Det. Mickey Hayden (Kiefer Sutherland) kills him, and thinks the case is closed. However, when Alice's mother gives him her necklace he is given one last vision that tells him Margaret is responsible.
Hayden confronts Margaret and she is unrepentant, saying she made the victims famous and that nothing can be proven. Hayden leaves Margaret, and she is confronted by Gideon Wood (Stephen Ouimette) who had been blamed as the supposed Jabberwocky killer. Hayden hears two gunshots (Wood killed Margaret, then himself). Hayden looks back in shock but realizes there is nothing he can do (and justice has been done). He then gets in a car and drives away with Dr. Swann.