Ensign Lemieux was a Human female who served in Starfleet as a security officer in the 23rd century.
In 2275, Lemieux was stationed aboard the USS Enterprise and served as Security chief Pavel Chekov's second in command. Following the Enterprise's stopover at Space Station Sigma One, Lemieux was forced to hunt down a terrorist aboard the ship following Chekov's near death at the hands of said terrorist. Lemieux ended up finding the terrorist with Chekov's help. (TOS novel: Death Count)