Prior to Season Three, Zack was busted with his drug dealer, Freebo. After that, Zack and Freebo didn't see each other for two years, during which time Zack started hanging out with Chicky Hines. When Chicky was arrested for a carjacking/homicide, Zack knew that he was innocent, and could identity of the real killer. However, Zack didn't provide an alibi to help Chicky and he was falsely convicted of murder.
When Detective Joey Quinn and Sergeant Angel Batista question Zack in an attempt to find Freebo, they find Zack and his girlfriend in possession of illegal drugs. Zack offers information that can prove the innocence of Chicky Hines if they will not arrest him. The evidence is verified but ADA Miguel Prado refuses to use it. Later, Maria LaGuerta gives the file to Attorney Ellen Wolf, and Hines is scheduled to be retried..