Lieutenant Karen Tracy is an Enterprise medical technician in Wolf in the Fold who beams down with a psycho-tricorder to probe Scott's lost memories and becomes the second murder victim.
Lieutenant Karen Tracy is a specialist in psychological technology aboard the USS Enterprise in the Original Series episode Wolf in the Fold. After Scott is found over the body of an Argelian dancer with no memory of the event, Kirk has her beamed down with a psycho-tricorder.
The instrument can produce a detailed record of everything a subject has done over the previous twenty-four hours. Tracy is left alone with Scott in a side room of Prefect Jaris's house to carry out the examination.
A scream brings the others running. Tracy is dead, stabbed many times, and Scott lies unconscious beside her, again remembering nothing. Her death deepens the case against the engineer until the ship's computer and Sybo's last words lead Kirk to Redjac, the fear-eating entity inhabiting Hengist.