Welcome to my 100% Achievement Guide for Ghost Files (MOAC)!
(Note, When there is no commentary in the video, i had to mute for copyright reasons)
You will get this right at the very end of chapter 6.
The real killer will (For some stupid reason) give you the note on how to complete the wire puzzle (Very easy, just matching up symbols).
After you complete this, it will unlock!
Go to 2:32:00 to see how to do this.
Hope This Helps!