What was Nina Myers motive?
Nina wanted to deflect her own involvement by fingering Jamey. Nina purposefully brings Kim and Teri to the safe house, essentially setting a trap for them to be recaptured. She then leads Teri to realize that she and Jack were lovers, turning Teri against her and giving her an excuse to leave.
Why did Jack kill Nina?
Jack called her worse than a traitor and eventually choked her against the wall. Believing that she had information relating to the nuclear bomb, Jack convinced her that he was an imminent threat to her life and would kill her if she had no useful information.
Why did Nina shoot Teri Bauer?
He informed CTU of this and she lost her job and her deep cover in the process and so wanted revenge. Nina captured Teri and shot her in the chest at CTU but when Jack realised his wife was in danger, it was too late as she was already dead.
Who was Nina working for?
Nina Myers was a double agent who worked for the Los Angeles branch of the Counter Terrorist Unit during Day 1. She was found out as a mole near the end of Day 1 by Jack Bauer and was arrested. She was responsible for the death of Jacks wife Teri.