Day 7: 9:00 AM - 10:00 AM - S7-E2
Continuity mistake: In the "previously on 24" recap, Jack tells Renee Walker "the Department of Justice is about to file criminal charges against me." But in that scene in the previous episode, he used the departmental abbreviation "DOJ".
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 ★