David O'Connell was the son of Pat O'Connell first mentioned by name in (68), when we find that he is in Pentridge with his father.
The scriptwriters stretch co-incidence to its limits by getting him to Wentworth in the next episode (69) in a prison work party so that Pat can talk to him and tell him why she's divorcing his father, they get sprung by Vera who tells the governor that they were "consorting" with each other.
When Pat gets paroled just before Christmas, she visits him in Pentridge and sees him get punched by one of the guards (75). Shortly after this, David escapes and seeks shelter with his friend Shayne.
When he goes to see his mother, the police are already on their way, and there is a shootout in which David kills a policeman (76). As a result his mother is sent back to Wentworth, and David becomes convinced that Greg Miller tipped off the police. With his friend Herbie, he plans to kill Greg but shoots Karen instead (78).
Herbie becomes worried about him and leads the police to their hideout, where David is recaptured (79) and is not seen again. In (80) Angela Jeffries tells Pat that David will plead insanity and as a result will probably spend the rest of his life in an institution. After his preliminary hearing goes badly (83), Erica tells Pat that David has hung himself in his cell.