Thicker Than Water

S3, E16: During the tense investigation of the recent bloody gang shootout, several officers, including Sully and Yokas, are questioned. Evidence suggests that one policeman was killed by another. Carlos is astounded to learn that he might be the father of a motherless, AIDS-infected baby. Meanwhile, on the first anniversary of her ex-partner's death, Kim becomes enraged at Doherty, her ex-husband, for encroaching on her time with their young son. Kim's anger affects her job as she confronts a self-destructive female gang member. Doc is visited by the father of a former patient whose debilitating injury might have been caused by Doc's error in treatment.