Day 3: 2:00 A.M.-3:00 A.M. - S3-E14
Continuity mistake: Chappelle shows Jack the security footage of him shooting Nina. He shoots her three times. He fires the gun with more of a gap between the gunshots on the footage than he did when we saw him kill her.
Answer: According to Jack in season 5, Nina was "deep cover" before the pair ever met, so it's safe to assume she was recruited before she joined CTU. As for what her primary mission was, who knows? Perhaps it was to gather sensitive intel and pass it on to her superiors. Given that she worked for an intelligence agency, it's not a stretch. Or perhaps we may find out in season seven.
Cubs Fan ★