Dead End
You will find it by using our walkthrough for this mission. From where you start, if you hug the left wall and follow it all the way to the shacks just outside the mill, you will come to a room with some TVs in it. The evidence is near the TVs. Alternatively, if you start from the exit, simply turn right and walk to the end. It's in the last room before going outside.
Old Mill
You will find it by using our walkthrough for this mission. In the first part of the area where you come across the two guys playing video games, the evidence is just on top of the TV. You can grab the evidence if you turn off the power to the TV with fuse box up stairs. While one person investigates it, the other will be busy doing something else and you can just grab it.
Descent
Just before you get to the first checkpoint, you'll be in a room with many stairs leading up, a couple of guards on opposite sides of the room and a door leading outside. The evidence is in this room on the long tables against the wall.
Factory Compound
This last evidence is in the final room of the area. It is heavily guarded and in the middle of the room so you'll need a disguise to grab it undetected.
