Books about: Police procedurals with otherworldly themes

[Phil]

Can anyone recommend novels about law enforcement agencies and private detectives working cases that turn out to be paranormal in nature (ghosts, aliens, monsters, etc)?

[Lynn]

Would Jim Butcher's Dresden Files series that starts with Storm Front be the sort of thing you're looking for? I think that all of his cases are likely to turn out to be supernatural for the 'private detective', Harry Dresden, is a wizard.

Rivers of London by Ben Aaronovitch is UK police based. This is also a first book in a series.

Blood Oath by Christopher Farnworth, US White House based, has a vampire secret agent. Again, the first in a series.

[Cynthia]

The R. Daneel Olivaw books by Isaac Asimov aren't paranormal per se, but he's a robot detective, it's "hard" science fiction by a master. The Wikipedia entry is very helpful
https://en.wikipedia.org/wiki/R._Dane...

[SamSpayedPI]

The PsyCop Series by Jordan Castillo Price, beginning with Among the Living.

[Lobstergirl, au gratin]

The Pendergast series by Douglas Preston and Lincoln Child sometimes gets a little paranormal/supernatural. The first one is Relic.

[...cats?]

Those Who Hunt the Night
Half-Resurrection Blues
The Atrocity Archives
B.P.R.D. (not a novel, a comic series)

[SamSpayedPI]

Dirk Gently's Holistic Detective Agency

[Cynthia]

and The Long Dark Tea-Time of the Soul

[Gillian]

Possibly I Am Not a Serial Killer. If I'm remembering correctly, it's not immediately obvious to the main character that he's after something supernatural.

[Kristen]

Felix Castor series by Mike Carey
The Last Smile in Sunder City
Dan Shamble, Zombie PI series
Hard Spell by Justin Gustainis
A Terrible Fall of Angels by Laurell K. Hamilton
The Affair of the Mysterious Letter (Fantasy Sherlock Holmes)
The Angel of the Crows (Fantasy Sherlock Holmes)
List of Discworld novels that involve the city watch solving crimes:
Guards! Guards!
Men At Arms
Feet of Clay
Jingo
The Fifth Elephant
Night Watch
Thud!
Snuff

[Cynthia]

Rinzler: A Noir Sci-Fi Thriller by Raya Jones