Possession - The Sharon Hayes Detective Series, #4

Sharon Hayes is back with a vengeance...and she's not alone. The voice in her head has given her some dire information: when Sharon killed her father, only his body died. His spirit has taken up residence in her head, and it's already crowded enough. Dewayne Doyle, Sharon's birth father, has always been an evil man, but now he is a malevolent spirit. Sharon turns to her partner at the NYPD Bronx Central Homicide squad: Archie Chong.
She confides her terrible secret to Archie, who doesn't blink an eye. "I will call on my fangxiangshi spirit, " he says. "We will have an exorcism." Archie has learned the skills of ancient China from his father; it's his side gig after work as a homicide detective, after all. Dewey Doyle is not their only problem. His very much alive cohorts in crime are still afoot, and they've each captured some innocent souls during their years as brutisha and vicious serial killers.
They have picked up some not-so-innocent passengers, too, and as the story climaxes, Sharon, and her allies discover the source of their power to possess the souls of those they kill: some very old gods are still in the world, turning evil men to their wills. Will Archie's ancient magic be a match for their power?