1. Progress through the story until you've got Residuum.
2. Find the Photo in Charlie's Mansion. Upper floor behind his office. Top left of the map: Map of Updaam.
3. Go to Fristad Rock in the Afternoon and find the Secret Bunker (Pumping Station) where Charlie and Fia took the photo. The note "Order of Operations" inside will tell you the code for Yerhva's Safe in Karl's Bay
4. Go to Karl's Bay, and enter Yerhva building close to entrance and open the safe. The document inside called "Aesthetics are Key" will give you the code for Wenjie's Office
5. Go to The Complex during Afternoon and defeat Wenjie, then go downstairs in the Lab Annex and open her lab.
This is important for the story, and continues your investigation.