She was a "black widow" who killed her husbands for their money, and one of Dexter Morgan’s earlier kills.
She promises sex to Dexter if he'll let her live, but it does not work.
The Ice Truck Killer has retrieved one of Dexter's latest victims, Valerie Castillo, from the ocean, leaving her body in the auto salvage yard. This results in a homicide investigation which finds a possible witness to her murder -- young Oscar. Worried that he might be identified by the boy, Dexter decides to eliminate evidence that would implicate him. After dark, he packs up his blood slide box and kill tools, and heads out to sea on his boat.
Dexter first throws his kill tools overboard, before reluctantly picking up the blood slide box that holds his valued trophies. He sits down, opens the box, and runs his fingers across the slides as he reminisces. When Dexter holds up the third slide, he remembers Cindy. In a flashback, she is lying on a kill table, with a cut on her left cheek. Her last words are, “I’ll fuck you if you let me go.”
The names of Cindy’s victims and their cause of death (medical supplies from a boyfriend) were obtained from a now defunct Showtime website.