Commander Torvald was an agent of the Celestial Intervention Agency and a confidante of its head, Coordinator Narvin. Torvald's name was later used by Andred, who killed the real Torvald and impersonated him.
Torvald was a particularly ruthless and questionable character, even by the standards of the CIA. On one mission, he travelled to pre-World War II Germany, where he posed as a Nazi official named Erich to save the life of Cecelia "Sissy" Pollard on 3 September 1939. She was to commit suicide at the outbreak of war. His motives were entirely corrupt. His intention was to hand Sissy over to a collector of historical artefacts. The plan was foiled by Narvin, President Romana and Leela, accompanied by the next regeneration of Torvald, who arrived from a point in Torvald's future to correct the timeline. They used a painful mind-wipe to erase his memories of having met his future incarnation and placed him back in his own timeline. (AUDIO: A Blind Eye)
Back in his own timeline, and without the memory of having encountered his future self, Torvald returned to his duties working for Narvin. Castellan Andred became suspicious of certain CIA activities, and in particular suspected Narvin of violent anti-alien tendencies, in contravention of President Romana's new policies. He made overtures to Narvin, claiming that his wife Leela had shown him the incompatibility of off-worlders living on Gallifrey.
Narvin easily saw through Andred's ruse, and when Andred invited Narvin to meet him in the Citadel catacombs, he guessed that Andred might try to assassinate him. He sent his most trusted agent, Torvald, in his place. In the confrontation, Andred and Torvald shot each other. Torvald was killed outright while Andred was forced to regenerate. Sensing an opportunity, Andred changed clothes with the unrecognisable corpse of Torvald and claimed his identity when found by guards. Believing Andred dead, Narvin covered up the incident and denied all knowledge of why Andred had suddenly disappeared, before eventually telling Leela that he had been killed by Torvald. Andred, meanwhile, continued to act as Narvin's loyal henchman in the hopes of uncovering any plot, until he revealed the truth to Leela, Narvin and Romana when they went back in time and confronted the real Torvald. (AUDIO: Weapon of Choice, Square One, The Inquiry)