He was an exceptionally talented, award-winning chef.
When Annalise Gallegos and Quinten Purvis decided to reveal the truth about the experiments performed on Talos I, Mitchell agreed to smuggle some food inside the container that Purvis intended to use for his return on Earth.
His talents were copied into a neuromod, and then implanted into Volunteer 37 as a test. After the Typhons broke out of containment, Volunteer 37 murdered Mitchell, cut up his body, and stored it in a box in the freezer of his kitchen. Volunteer 37 then masquerades as Mitchell when he confronts the player in the Crew Quarters.