Chapter 4: Einswald Prison
As soon as the mission starts, walk forward and enter the first opening on the left to enter the room there. The letter will be on the table to the right.
As soon as you get the laser cutter, exit out of the room and go down the hall which will have a fence on the right side. Cut an opening in it and then grab the plate from inside.
Just after you reach the charging station for the laser cutter, enter the next room and before you climb through the window, cut open the fence on the right to find the picture frame there.
Once you use the key to open the door in to the coal loader room, go to the far left side on the bottom floor and there will be a pile of coal. Look around the bottom of it to see the shining gold nugget.
Once you lay head to the orange upstairs section that is lined with lockers, continue down the hall and two guards will rush you from a room on the right. Kill them and then enter the room to find the helmet at the bottom of the locker.