Jade Carnegie was a minor recurring villainess from Criminal Case: Mysteries of the Past. She was a villainous counterfeiter who was first mentioned (without her name being known at the time) in case #38, "Stockbroken", after it was revealed that investor Easton Belmont was conspiring with her in her greedy scheme (and had killed stockbroker Abner Milton when he uncovered countfeit bills in Easton's possession).
In the following case, "Apprehend Me If You're Able", the player and Maddie O'Malley stormed Jade's headquarters at 247 Baker Street to arrest her, only to find the counterfeiter killed via a bullet to the neck. Over the course of the investigation into Jade's murder and her various crimes of greed, it was revealed that she was the former protege (and current lover) of Flying Squad consultant Diego del Lobo and she previously committed her counterfeiting scheme in Spain under the alias Juanita Cortes. Jade had stolen a counterfeiting plate Diego made as a challenge to himself, while threatening to frame him as the counterfeiter if he turned her into the authorities.
Ultimately, Jade's killer was revealed to be Gail Harper, an exchange officer and a friend of Jade's from Spain who had become a cohort in Jade's illegal business, distributing Jade's counterfeit bills through her exchange office. But eventually, the evil Jade became impatient and started spending the counterfeit money, driving Gail to kill her out of fear that her recklessness would led to them being caught.