Jonsey was a Human of male gender. During the Galactic Civil War, he was a stormtrooper within the ranks of the Imperial Navy.
In the year 1 BBY, Jonsey received orders to join the stormtrooper detachment stationed on the Imperator, an Imperial I-class Star Destroyer. As a member of the platoon under the command of Cadet Leader Kyle Katarn for Katarn's Omega Exercise, he took part in the ensuing battle that unfolded on AX-456. When the platoon reached the communications room, Hong instructed him to extract the memory modules from the transmitters prior to their departure from the base. Jonsey, along with the remaining troopers, fell back to the base's cafeteria, where Rebel reinforcements eliminated all but a handful of six stormtroopers.