Zack Mohr is the abusive father of foster child John Lasky. Johnny and his mother Tori Lasky were thrown out of the house as Johnny fought back against Zack beating them both more and Zack was done with them both. Tori was addicted to drugs and went into rehab, so she placed Johnny in the foster system and waited until she was sober to get him back.
When Johnny was murdered, Zack was chastised for his abuse and even suspected of Johnny's murder. Zack had an alibi of being at a nightclub, and his new, abused girlfriend Delia revealed their apartment was robbed, with Johnny being revealed to be behind the heists. He recruited his foster brothers, Chris Pollit and Andy, to steal from Zack to pawn the items and have enough money to live with Tori on their own. Chris killed Johnny in a fit of rage, when Johnny caught him spending the money for himself, and the latest heist had Delia as a witness.
It's unknown what penalties Zack faced for domestic abuse. (L&O: "Born Bad")