Chapter 2 Remnant's: Statue/Key; After Sneak Kill Instruction, Into shack, after climb instruction, through window, before going through gate look to the left of gate on wall.
Chapter 3 Claws of the Horde: Statue/Key; One hanging on wire between two houses near gate. One on top of a wall near the first key to the left of the haunted sniper. Both can be shot down or hit with a glass bottle. One half way up the support structure for the guard tower opposite the barn.
Chapter 4 The patient: Statue/Key; One hidden inside of the body that a haunted was working on in the hospice.
Chapter 5 Inside one of the jail cells containing haunted's which you pass by when going to activate the control panel to open the trap.