Martinez's career before the cameras began at the age of 15, when her mother suggested that she try her hand at modeling for actress Jennifer Lopez's new clothing line. Martinez was selected for the job over 5,000 other hopefuls, and headed to Los Angeles, California, to make her way in the modeling business. She was soon featured in the pages of numerous publications, including men's magazines like Maxim, which in turn led to appearances in music videos by Justin Timberlake. Martinez made her acting debut via the Fox Entertainment Group-owned MyNetworkTV, a television network/syndication service that was initially dedicated to broadcasting English-language telenovelas. Martinez starred in two such series for the network: "Fashion House" (2006), with Bo Derek and Morgan Fairchild, and "Saints & Sinners" (2007). When both series ran their course, she returned to music video appearances, and was initially cast as a major character in the NBC series "Chuck" (2007-2012), but was written out of the show before its initial airdate. Martinez made her feature film debut in "Death Race," director Paul W.S. Anderson's remake of Roger Corman's dystopian cult classic "Death Race 2000" (1975). She then segued s a brief stint as a cast member on the short-lived crime drama "Detroit 1-8-7" (ABC, 2010-2011). The following year, she enjoyed a recurring turn as a police detective on the popular "CSI: NY," which led to supporting roles in major features like "End of Watch" and "Broken City" with Mark Wahlberg and Russell Crowe. That same year, Martinez scored her first bona fide hit project with the CBS series "Under the Dome," which cast her as a sheriff's deputy in a small town suddenly cut off from the rest of the world by an unseen barrier. The program was renewed for a second season in the summer of 2013.