NEOK'S PROFILE

You can do this any time before initiating the wraith extermination plan (by talking to Cyrus).

Cyrus gives you the biggest clue right at the end. You need to establish that one of Erina's children is still alive. Ramius dies no matter what you do, so that leaves Regina.

You've been given some clues as to her whereabouts. What you need to do is find all of them. If I recall, there were something like 3-4 clues. The ones I remember are:

1. Check the desk in the room with the friendly mutant.
2. Look at the Wellington family portrait in Victor's room.
3. Rescue the servants and talk to one of them (?)
4. Read the library books (?)

In any case, if you get all the clues, the next time you talk to the friendly mutant, it'll trigger an event. After that, you'll be able to continue after the point where the game would normally end.

And just some hints for the last part of the game since it's really obscure:

1. You need to use the item from the inventory screen.
2. Your position on-screen relative to the wraith matters.
3. One of the dead scientists has a note which hints towards what you need to do. See if you can "trap" the wraith.

If I recall correctly..

You need to do something in the mausoleum north of the manor (past the henge maze)

There is a note in one of the servant's rooms that pertains to a hidden switch in the mausoleum.

You'll also need to know the contents of a certain book in the library in order to proceed through there.