Queen's Menagerie. Crown and Country, #1

Menagerie Special Agent and tiger shifter Mordecai Pope is charged with apprehending the villain who litters the river's edge with the half-shifted corpses of his colleagues. As he examines the bodies he discovers the murderer has not only taken tissue samples and blood, but removed the talises--a tattoo used to prove the shifter's registration and animal class--When an unregistered, half-shifted man is found alive and repeating the Reaver word for venom, Mordecai begins to suspect there are more to the murders than meets the eye.
Lady Evangeline Murray has spent the last seven years cursing the memory of her fiance who was lost on an exotic expedition to the far ends of the world. His pursuit of scientific discovery often ovestepped the bounds of morals and propriety. Through the years, Evangeline has kept her own counsel over the man all of society dubbed "a man without peer" but whom she felt little respect. To prove his madness and free herself from binding betrothal laws, Evangeline has embarked on a perilous venture of her own.
In possession of her finace's notebooks, Evangeline has painstakingly recreated his experiments and deciphered his secret codes even though scientific exploration is illegal for women in East Angelia. Now her work has brought her under the suspicion of her new beau and Menagerie Agent, Mordecai Pope. When Mordecai's case and Evangeline's past collide, they must work together to find a killer bent on creating an army of shifters and setting them loose on the world, even if it means losing each other forever.