Complex sentence: She quit her job at which she had a promising career, and started to work at the Seattle PD morgue, not only to satisfy her urge for brains, but to help the Police Department at solving crimes as a "psychic" consultant.
Split into simpler sentences: She quit her job at which she had a promising career, and started to work at the Seattle PD morgue. But not only to satisfy her urge for brains, but to help the police department at solving crimes as a "psychic" consultant.