She was played by Blair Brown.
Margie Winters is the mother of teenage model Dara Winters, who was found dead near a stretch of country road. She appeared as a mourning mother when interviewed at her home by Horatio Caine and his crew, though it was later revealed as a cover for her controlling and abusive personality. Dara's modeling career wasn't by choice; Margie forced her into the industry, which included dressing Dara in suggestive clothing. The callous villainess even forced Dara to wear a diaphragm, sending her a message that she should sleep her way to the top. Dara ran away from Margie's control and continuously went to her friend, Julie Morales, a cadet at an academy for troubled girls.
Dara went to the academy after an argument with Margie, who tracked her close to the area late one night. She expressed shock over Dara cutting her hair and attempted to force her to return home and to the life that Margie was forcing her into, only for Dara to refuse. In response, the evil Margie slapped Dara, who later ran away to a wooded area. While running, however, Dara tripped and hit her head on a rock, which killed her. Margie drove away afterwards; doing so with little concern for her daughter's whereabouts.
After interrogating both Julie and senior cadet Valerie Barreiro, the CSI crew connected Margie as the last person to see Dara and brought her in for questioning. Margie defended her controlling actions, stating that Dara was "special and going places," but she was throwing it all away. Horatio later uncovered the diaphragm found at the scene, and revealed that both Margie's and Dara's prints were on the object. After this, Margie was arrested (off-screen) for her role in Dara's death.