 He explains that he kills according to a moral code taught to him by his foster father Harry Morgan, who, as a Miami police detective, taught Dexter to kill only those who "deserve it".Flashbacks reveal that Harry first decided to impart these "lessons" upon Dexter after discovering that the boy had been killing neighborhood pets.Dexter is contacted by his foster sister Debra (Jennifer Carpenter), a vice officer in the Miami Metro Police Department.