ABANDONED. Horror/Thriller/Dark Comedy book (Similar to plot of 'Dirk Gently' books)

[Ali]

Hey everyone! My boyfriend keeps mentioning a book he read years ago that he fell in love with but has been unable to find since. The plot seems similar to that of the Douglas Adams 'Dirk Gently' series, at least for the set up anyway. These are the only plot points he can remember:

The main character works in a hotel and goes to check on a room one day, to find a man hanging, in an apparent suicide.
Once he gets home that evening, the ghost of this hanging man appears to the hotel worker telling him that his death was a murder. He explains that the hotel worker is the only person that can see his ghost, because he was the first one to find the body.
The two then go about trying to solve the mans murder (which POSSIBLY has something to do with a cult).

That's all I got. I know it's a shot in the dark but maybe someone has read it too and remembers. There are funny moments to it also, apparently.

Thanks!

[Lobstergirl, au gratin]

Ali, are you still looking for this or did you find it?

[Kris]

No response, moving to Abandoned folder.

Ali (OP) was last active on the site in December 2016.