If Kurzen knows Thorsen's secret, then we have a spy in our midst. We must determine how the secret was leaked!
Thorsen's contact within Kurzen's camp was Bookie Herod. Herod is Kurzen's logistics officer and knows everything about the running of Kurzen's Compound. If you can get Herod's notes or records, maybe we can find out how Thorsen was discovered.
When we were still with Kurzen, Bookie's office was on the top floor of the camp's only two-story house. His records are probably still there.
Completion
These are Bookie Herod's notes and records.
Among them are: a list of supplies within the camp, material requests from Colonel Kurzen, and various letters and correspondences.
You must go into Kurzen's Compound and locate Bookie Herod's office. You can find this upstairs in the only two story building in the compound. There are several Kurzen Jungle Fighters and Kurzen Headshrinkers around, so you will need to clear your way in.
Once you have cleared the enemy from the house, look around to find a pile of books and crates. These are Bookie Herod's Records.