As an outgoing child, Rivas grew up entertaining his family with impressions and original characters. He was so committed to his dream of becoming an actor that in 1985 he graduated from the prestigious UCLA drama school with an MFA. He landed his first acting job, the HBO gambling comedy "Glory Years," just two years later, and began working steadily on both the big and small screens. In 1987 he played a fictional bandleader in the well-received "La Bamba," which chronicled the tragically short life of singer Ritchie Valens (Lou Diamond Phillips), and spent the next several years in supporting roles on shows such as the cop drama "Jake and the Fatman" (CBS, 1987-1992) and the glittery nighttime soap "Knots Landing" (CBS, 1979-1993). After being cast as a low-level gang member in the brother-against-brother drama "Blood In, Blood Out," Rivas became even more in demand, appearing in four or five projects a year. Beginning in 2001, he portrayed Sam Vega, a gang unit detective turned forensic foot soldier, on the popular CBS procedural "CSI: Crime Scene Investigation." When he wasn't busy chasing criminals in Las Vegas, Rivas was cornering them in Washington, D.C. on "The District" (CBS, 2000-04) and in Albuquerque on "Breaking Bad" (AMC, 2008-2013). In 2008 Rivas branched out into producing with the musical drama "Moe," an adaptation of a play focused on the last days and delusions of a theater director dying of AIDS. He later returned to the familiar blue uniform with a two-episode stint as a wary detective on the first blood-soaked season of FX's critically-acclaimed "American Horror Story."