María LaGuerta died from a gunshot wound in the TV series "Dexter." She was investigating the truth about Dexter being the Bay Harbor Butcher and came very close to exposing him. Dexter had planned to kill her to protect his secret, but before he could, his sister Debra Morgan arrived. During a confrontation, LaGuerta woke up and tried to persuade Debra to kill Dexter. Instead, Debra shot and killed María LaGuerta to protect her brother's secret. So, while Dexter was involved and had intended to kill her, it was Debra who actually pulled the trigger.