When you jump through the skylight in the roof in the great hall, clear the place of enemies and run behind Mason. When you get the room with the stairs leading down (first picture above) search for intel (1/3). It is lying on one of the shelves on the left (second picture above).
The second intel can be found in the slum area. This is a very vast area, and you can get here from many places. If you located the church, then when you look at it and then exactly to the left, you'll notice a hole in the wall. Go through it to get to the correct apartment. If you came here from the south, quickly kill the enemy harassing a civilian (first picture above) and then head for the door on the left. Inside, on the counter on the left, directly opposite the hole in the wall, you will find intel (2/3) (second picture above).
After the third cutscene, showing old Woods and young Mason's talking, immediately after regaining control over the character go forward all the time. Stop only when you see the last intel (3/3) (picture above) on the opposite sink.