N order to catch the spy andsuccessfully foil his plan, you need to eavesdrop on his radio conversation in the control tower. If you stick to my path, you’ll have no problems. It seems that a lot of people have run into bugs and a somewhat unexpected instant failure. One thing that is very important is that you follow the following instructions.
Note that this is true even if you have completed Three-Card Bounty and they’re in Camp Forlorn Hope. You can figure out the exact times of the break-ins by either checking the log at the control tower entrance or by talking to the First Recon Snipers to learn that the lights come on around 1 AM each night. If you talk to Boyd, she’ll mention Contreas' skimming and some odd break-ins at the control tower. There is a separate quest to reveal his corruption, but Contreas isn’t related to the spying. He’ll point you toward the head of the Military Police, Boyd, and a corrupt quartermaster, Contreas.
He’ll ask you to find out who the spy is by helping out Curtis with his investigation.
He’s inside the terminal, with a small office to the left of the main terminal entrance. Colonel Hsu can give you the mission at Camp McCarren.