Mara Tyler was a field agent at CTU Los Angeles during Day 5. She appeared to have a working relationship with Jack before he left CTU.
Mara Tyler escorted Jack Bauer back to CTU Los Angeles after the crisis at Ontario Airport. On the way, she commented to him how shocked she was to see he managed to stay "dead" for so long. When they entered CTU, and all the staffers looked at Jack in disbelief, she told him how everyone was sure he was dead. Once she brought Jack back to CTU, she was dismissed by Lynn McGill.
Mara Tyler: Year and a half. How'd you manage to stay invisible for so long?