Rosa Diaz

Rosa Diaz is a smart, tough, and mysterious detective. Rosa previously attended a parochial school, where she was a model student and had a favorite teacher, Ms. Weeniercool. She also studied ballet at the American Ballet Academy, but was expelled for "hitting on the ballerinas". She mentions in The Mattress that her ballet teacher, Ms. Miriam, would often complain to her about her "posture, technique, and pink hair". The pink hair may be a reference to Stephanie Beatriz's hair, which sometimes has pink highlights in it. Rosa turned out to be a classmate of Jake Peralta, who was in the police academy, where the two became best friends.

Rosa Diaz is an intelligent, tough, and mysterious detective (it is revealed that her name may not even be Rosa Diaz, as she assumes multiple identities for different people). Although Diaz is a loyal and effective member of the squad, her anger management issues and lack of empathy terrify most of her coworkers. She is highly secretive about her personal life and refuses to let any of her coworkers visit her home, despite living very close to the police station. She is shown to own many weapons and believes that every woman should own an axe. Rosa also owns several swords. She is always carrying a large knife hidden on her person.