She sets her own loft on fire and helps Santos Jimenez attack Dexter, believing that she and Dexter are closest in times of crisis.
She was raped and killed in a snuff film by Jamie Jaworski.
Brian later attempted to kill Debra when he thought she was staying at Dexter's apartment, but instead fell into a trap set by Dexter, who then brought him to the cooling room where Brian committed his murders.
Matthews is portrayed as having flaws: nominal racism and serious political ambition, neither of which are ever shown in the novel series.
At the end of the ninth episode of the first season, it was implied that Brian had murdered Joseph Driscoll while in disguise by injecting.
Dexter's suspicions are confirmed when he examines the shirt Miguel gave him after the murder of Freebo.