Little in known of the life of the criminal who identified himself as Ivan Caroff in mid-1942 while working at the  Carey Clinic in the suburbs of Gotham City.  The clinic was owned by his father, Carl Carey, a well-known medical researcher.  It is not clear if the name "Caroff" was a nom du crime or if for some reason, such as adoption, that he and his father did not share the same last name.

Caroff came to the attention of the law when he used his father's research apparatus to conduct unnatural experiments into the animalistic tendencies inherent in all humans.  He developed a device the rays of which brought out specific traits and he used it to devolve or re-evolve subjects into beast men with specific qualities.  His first known effort involved using his device on a man named Klaw, where it provoked the emergence of panther-like features, giving him cunning, agility and night vision.  Caroff dispatched Klaw to rob a local bank but Klaw's transformation had also evoked a panther's predatory instincts, causing him to murder one of the bank guards.  Returning to Caroff, he could not explain his actions.  Caroff lectures him on his basal tendencies and then returns him to human form.

The following day, the authorities have discovered the mangled body of the guard and an autopsy suggest he was killed by a large animal.  Coincidentally, Doris Lee has taken Ted Knight to Carey Clinic to try to diagnose his mysterious spells of weakness.  Caroff emerges to meet with the new patients and as they chat, Woodley Allen contacts Knight via their secret transmitter to discuss the bank guard's death.  Knight feigns a fainting spell and as Caroff takes him to a roof to lie down, he switches to Starman and flies off as soon as he is left alone.

Hearing the details from Allen, he goes on patrol and sees a wolfman chasing a screaming girl.  Swooping into her rescue, he is embarrassed to find that its movie set and the wolfman is an actor.  Apologetic but suspicious, he follows the wolfman back to Caroff where he sees hims transform back into a man.  Crashing through the window, Starman attempts to interrogate Caroff but the scientist claims he had just pulled off an adherent mask and the orderlies intervene to help him.  Mollified, Starman goes to leave but his stunned by a magic eye hidden in the doorway as he exits.