Nurse Mary holds a unique place in the series' lore as the catalyst for Dexter's "code":
In certain depictions, she utilized consecutive, low-level doses of potassium nitrate delivered via syringe. The human body naturally processes large quantities of potassium, making the buildup lethal but nearly unnoticeable to standard forensic pathology. nurse mary dexter
: Dexter discovered Mary's activities when Harry was hospitalized for a heart attack and began deteriorating under her "care". Nurse Mary holds a unique place in the