Sheriff Diaz works for the Evergreen County Sheriff’s Deparment as a county officer who first comes into play on 13 Reasons Why during the investigation of Bryce (Justin Prentice)’s murder.
He plays a big role throughout the season, speaking with all of the classmates and trying to identify who caused Bryce’s death, then later, where the steroids found in Bryce’s car came from.
Sheriff Diaz becomes intimately enmeshed with the football team after conducting several searches and talking to the whole team in the hopes of understanding better what went down on the evening of homecoming.
When Sheriff Diaz begins to suspect that Clay had the intention to kill Bryce in order to either get justice for Hannah Baker (Katherine Langford) or because he was jealous of the fact that Bryce was hooking up with Ani (Grace Saif), he eventually arrests Clay in front of other students following a Liberty High assembly.
Of course, it comes out that Clay is actually innocent of the murder, and that Zach (Ross Butler) had actually seen Bryce after Clay.
Now in Season 4, as emotions regarding Justin’s health run high, Clay runs to the County Sheriff’s Department claiming he has a gun when he doesn’t actually, because he wants someone to notice and help him. “I promise no one will hurt you,” the sheriff says to a distressed Clay.