Lennert

Lennert was an FBI agent during Day 7 who was secretly working for David Emerson's terrorist cell.

Day 7
Lennert received orders from Tony Almeida to assist Alan Tanner in escaping the building where the FBI had a tight perimeter. Lennert met up with Tanner in the basement and gave him an FBI uniform to slip out unnoticed. [[Jack Bauer noticed, however, that Tanner's shoes did not match those of the other agents and reasoned that there was a dirty agent, but did not identify Lennert.