Nicola Petrosian is the villainess from "Baby Blue," a Season One episode of Person of Interest.
She was played by Kate Hodge.
Nicola Petrosian is the wife of Adnan Petrosian, the owner of Petrosian Construction. She found out that Adnan had an affair with a young woman named Claudia Cruz, which resulted in Claudia being pregnant and giving birth to a girl named Leila. Nicola later confronted Claudia and killed her, knocking her out with a blow to her head and then setting her house on fire. She also hired an Eastern European gang to abduct six month old Leila.
Nicola's reveal came when Reese confronted Adnan at their home, as it was revealed that Nicola's fingerprints were on the murder weapon: a lamp. Nicola admitted to killing Claudia and stated that she did so to "clean up her husband's mess." Regarding Leila's abduction, the evil Nicola admitted to that as well, and stated to Reese that there was nothing he could do about it. While not shown on screen, Nicola was arrested for her crimes.