The Security Chief was the War Lord assigned to deal with the humans who had successfully resisted being hypnotised into participating in the war games and fought against them as the resistance. He suspected the War Chief and the Second Doctor of plotting together to betray the War Lords. The Security Chief and the War Chief both shared an antagonistic relationship, and it deteriorated as the humans and the Doctor worked together to stop the War Lords.
The Security Chief interrogated the Doctor, but he didn't have much luck because of the Doctor's Time Lord training which prevented the mind-reading machine from working.
Community content is available under CC-BY-SA unless otherwise noted.