Emerald Deception. Lowan, #14

Meet Lowan, a telepathic alien working as a private detective in the 1930s!Marilyn Chambers finds herself hunted by phantom pursuers and haunted by dark secrets that could upend her crumbling marriage. Thrust into a deadly game of cat-and-mouse, she discovers evidence that challenges everything she believed about her husband and her past. Lowan takes the case and reluctantly teams up with a rival detective, Fritz Gallop, but the emerald found in Marilyn's purse-presumably the killer's target-turns out to be nothing but a decoy.
The real stakes are high enough to make even Fritz Gallop back out. With danger stalking every shadow and a murderer on his tail, Lowan plunges over his head into a tangled web of forged identities, insurance fraud, stolen microfilm, and a vengeance-fueled list that could expose a criminal empire. S. E. Grosskopf's writing is strongly influenced by the old pulp fiction magazines and Golden Age radio dramas of the 1930s-1950s.
If you like fast-paced action and mystery with a dash of urban fantasy and quirkiness, then you'll love these books. This is the fourteenth book in the series. The books follow chronologically. Reading them in order is recommended.