Stephanie Carson

Stephanie Carson is the main villainess from "Calling the Shots," episode 3.02 of Motive.

She was played by Ally Sheedy, who also played Mr. Yang on Psych.

Stephanie Carson is an investment advisor who was secretly running her own Ponzi scheme; embezzling money from her clients. One of her clients was Erica Grey, a housewife who was working as a prostitute under the name Sienna. After learning that Stephanie scammed her, Erica confronted Stephanie and told her that she wanted her money that she invested--$50,000--back, or she would go to the police.

Stephanie met Erica at her apartment, appearing to acquiesce to her demands. While Erica was putting pen to paper, though, the evil Stephanie pulled out a syringe and killed Erica with an overdose of pentobarbital. It was right after the murder that Stephanie learned about Erica's side job as a prostitute--when she saw the leather gear in her closet. With that, Stephanie decided to set up the crime to look like one of Erica's male clients committed the murder, while drawing the word "SLUT" on her forehead.

Personality
Regarding Stephanie's personality, she was shown as a controlling mother to her daughter, Madison, and she actually suspected Keith and Erica of having an affair--though that was not Stephanie's motive for murder. Stephanie was arrested for Erica Grey's murder.