Following Arthur's "disappearance" (as Arthur Mitchell is assumed to be alive and has gone into hiding), she likely holds onto the fear that he's always out there despite not having to live under the constant watch of her husband. Unfortunately, she finds herself victim to "Trinity" along with her daughter, leaving only their son Jonah alive.
Sally is an older woman with long, brown hair and blue eyes with a bright white smile. She wears the typical house-wife attire, almost always seen in dresses with flower patterns or even an apron.
Sally severely suffers from the effects of Battered Person Syndrome, so much that her "mask" is all she can control in her life. No matter what, she tries to live in the reality that she must pretend that their lives are perfect but she lives in constant fear of what her husband Arthur Mitchell could do to her and the family. She personally begs "Kyle Butler" (who is actually Dexter Morgan) not to tell Arthur anything regarding Rebecca Mitchell's awkward advance on "Kyle", in emotional fear of what could happen to her or the family because of it but the entire time she tries to keep up a nervous smile, even though it quickly begins to fade as she becomes more and more serious in her fears of what he could do to her.
Despite this fear, she does love Arthur and to such a degree that she would actively put herself in harm's way to make sure he's safe. Another unfortunate symptom of the same syndrome.
Because of this fear and love for her husband, it allows him to do whatever he wants to the family.
At first it appears she has an ideal family. The entire family appears loving, is a pillar of the community, church-goers, and involved in a project to build homes for the homeless. However, this is revealed to be a facade: Arthur, is very controlling and abusive. His wife, fearing her husband, perpetually puts on a cheery facade and is willing to let her daughter continue a perceived affair with Dexter as long as Arthur remains unaware.
Sally is killed by Jonah Mitchell, her son. She was still in love with Arthur and constantly praised him and blaming Jonah and her daughter Rebecca Mitchell for everything he did. This forced Rebecca to commit suicide and Jonah killed her in a fit of rage. He later asked Dexter Morgan to kill him for what he did, but Dexter let him go and told him to forgive himself. It is clear that in Dexter's opinion, Sally had it coming.