Sandy vazquez

Nita finally has Fabricio, the boy who betrayed her to the black market, within her grasp. But when proof that Kovit’s a zannie - a monster who eats pain in order to survive - is leaked to the world, Nita must reevalute her plans. With enemies closing in on all sides, the only way out is for Nita and Kovit to take on the most dangerous man in the world: Fabricio’s father. He protects the secrets of the monsters who run the black market. Stealing those secrets could be the one thing that stands between Nita and Kovit and certain death in the thrilling conclusion to the trilogy.

Nita doesn't murder supernatural beings and sell their body parts on the internet - her mother does that. Nita just dissects the bodies after they've been "acquired". Until her mom brings home a live specimen and Nita decides she wants out; dissecting a scared teenage boy is a step too far. But when she decides to save her mother's victim, she ends up sold in his place - because Nita herself isn't exactly "human". She has the ability to alter her biology, a talent that is priceless on the black market.