Zoe Mercado is a minor villainess from "Art Imitating Art," episode 4.20 of Elementary.
She was played by Lauren Vélez, who previously portrayed the villainous Maria LaGuerta on Dexter.
Zoe Mercado is a lab technician hired by the evil Krysta Pullman to work on the body of a woman named Marissa Kagan, who was revealed to be Krysta's illicit lover. Zoe was hired by Krysta because she is a "dry labber"; manipulating reports to make sure police arrest who they believe committed the murder. Zoe's actions led to Lewis Bowman being convicted of Marissa's murder. In actuality, it was Krysta's wife, Terri, who killed Marissa in a jealous rage. Zoe was interrogated by Sherlock and Gregson over her actions, and though her fate was not revealed, it is assumed that Zoe was arrested for her role in covering up Terri's murderous deed.