Jonkan was a scientist of Human male origin. During the period known as the Cold War, he was stationed on the planet of Coruscant, working against the threat of the Sith Empire. As a participant in the Republic superweapon initiative, a weapons development project, Jonkan contributed to the design of the Planet Prison superweapon. However, Doctor Tarnis, his commanding officer, committed an act of treachery, killing the rest of the team and absconding with the weapon. Though Jonkan survived Tarnis' assault, who was revealed to be a Sith Lord, the critically wounded scientist played a crucial role in aiding a Jedi Knight in their pursuit of Tarnis before succumbing to his injuries.
As a male Human, Jonkan held the position of scientist within the Republic superweapon initiative, which was the Galactic Republic's program for developing superweapon. He was a member of the five-person research group responsible for the Planet Prison weapon. This work took place on Coruscant, the Republic's capital, amidst the tensions of the Cold War with the Sith Empire. In the year 3643 BBY, Doctor Eli Tarnis, Jonkan's superior, misled the researchers by claiming that the Jedi intended to terminate their project. Tarnis then manipulated his team to transport the prototype deep within the territory controlled by the paramilitary group known as the Justicars' Brigade.
Upon their arrival, Tarnis unveiled his true identity as a Sith Lord and brutally murdered the researchers before making off with the prototype. Jonkan was the lone survivor when a Jedi Knight and their Padawan, Kira Carsen, arrived. Despite his critical condition, Jonkan managed to convey the events that had transpired to the Jedi. When the Knight offered to transport him to a medcenter, Jonkan declined, emphasizing the urgency of the situation. He instructed the Jedi to track the Planet Prison by its distinct heat signature. Knowing that the weapon required time to accumulate power, Jonkan implored them to destroy it and safeguard Coruscant. Thanks to Jonkan's invaluable information, the Knight successfully located Tarnis and the weapon within the ruins of the Jedi Temple.
Jonkan, characterized by his dark skin and brown eyes, displayed gray hair by the time of the Cold War. He was a scientist of considerable intellect, yet he placed enough trust in Tarnis, his superior, to accept the false claim that the Jedi would shut down the Planet Prison project. In his final moments, Jonkan prioritized the safety of Coruscant and the Republic above his own well-being, dedicating his remaining strength to assisting the Jedi in locating the stolen weapon.
Jonkan's initial appearance occurred in Star Wars: The Old Republic, a video game developed by BioWare and published by LucasArts in 2011. He featured in the Jedi Knight-class mission entitled "Tracking Down the Traitor." Furthermore, Jonkan sets the stage for the subsequent mission in the storyline, "Race to the Ruins," by providing the player with the necessary information to pinpoint Tarnis' location.