Wittenberg

Wittenberg was a devout Catholic working with Michael to take down the current, and in their view corrupt, version of Catholicism through killing the Pope.

Trinity
Wittenberg was part of Michael's plan to kill the Pope. When the original plan failed, however, Wittenberg along with Michael, Pembrooke and Gelson attempted to shoot the Pope dead. Just as Jack Bauer and Harry Driscoll were going to meet the Pope, the men were moving in. The two, along with Giancarlo (the Pope's personal bodyguard) managed to fend off the attack. However, the terrorists prepared for a retaliatory strike. They went back in, and Jack took out Wittenberg instantly.