.. How do I find the ghost in this location?

After you get off the phone with Detective Durkin, take a look around. There's no obvious ghost, and there aren't a lot of places a ghost could be.

There is a door right here, but it's locked. When faced with a locked door in this game, your first tactic is not to go looking for a key; rather, it's time to send in the dead guy.

Joey, as a ghost, can float in midair and phase through locked doors and solid walls. So switch over to Joey and click on the door to send him in to look around.

I can't find my way around this building!

This first room is a sort of lobby. Exit through the door at the right to find yourself on the second floor landing --

-- where you can see a ghost going up the stairs to the third floor. Joey can't follow her because as Rosa's spirit guide, he's tied to her and can't go more than a couple dozen yards from her.

So the next step is to get Rosa inside that locked door. I guess we do have to go find a key after all.

How do I unlock the door for Rosa?

Once Rosa is inside the building, Joey can go through the door at right and then up the stairs to find the ghost.

How do I find out more about the ghost?