Mission 2: Celerium
Intel Item 1
When you reach the helipad and destroy the helicopter, you can find this piece of intel in a small room directly to the left of the pad. Enter the room there and it will be sitting on the desk,
Intel Item 2
Once inside the underground lab, fight through the enemies until you come to large room with a large staircase at the far end in the center with two yellow stripes running up along each side of it. When you see it, go to the left side and there will be an open office there where you can find the intel sitting on a desk.
Intel Item 3
When you reach the small room where you are shown the Celerium, you will soon exit as a rush of enemies appear. Deal with them and then go to the far, opposite end, of where the Celerium chamber was to find the intel sitting on a desk.