Lennert

Lennert was an FBI agent during Day 7 who was secretly working in league with the Taylor administration conspiracy to actively aid David Emerson's mercenary group.

Day 7

Lennert received orders from Tony Almeida to assist Alan Tanner, the man who shot down Gabriel Schector and Ari (the FBI's only leads in the investigation into Almeida) in escaping the Columbia Building, where the FBI had a tight perimeter. Lennert met up with Tanner in the basement and after a brief standoff, Lennert informed Tanner that Tony had sent him. Lennert gave him an FBI uniform to slip out unnoticed.

Jack Bauer realized, however, that Tanner's shoes did not match those of the other agents and reasoned that there was a dirty agent who helped him escape. After deducing that there must have been at least one dirty agent, Jack and Renee Walker decided to avoid notifying the rest of the FBI of Tanner's escape and pursued him on their own.

Background information and notes

• It is not explicitly stated if Lennert faced justice, or if he was directly aiding Iké Dubaku (he might've been only aiding Tony). The names of all the government agents on the payroll of Iké Dubaku, almost one hundred, were decrypted by Chloe O'Brian from a chip found in Dubaku's midriff in "Day 7: 5:00pm-6:00pm." It is possible that Lennert's name was among them. Furthermore, Larry Moss reports finding two moles inside the FBI beyond Erika; likely referring to Lennert and Sean Hillinger.