Steel-Eyed Death (S20E13)

When a family of four is found murdered in their home, Detectives Cyrus Lupo (Jeremy Sisto) and Kevin Bernard (Anthony Anderson) discover that the deaths may be related to the deceased teenage daughter's troubled friend, Bonnie. As Lupo and Bernard track down Bonnie, the detectives become aware of another suspect, Justin, who suffers from post-traumatic stress disorder making the case more complicated when both suspects' mental states come into question. (iTunes)