"I made it bad enough, Johnny. Don't make it any worse."
Mary and her two children, John David and Sandra, were frequently abused by her husband Sam, who was a religious, fanatical alcoholic. She made many attempts to stop Sam from abusing their children, but he always wound up dominating her, and she couldn't leave him because she was too frightened of him. On the Halloween of 2002, Sam locked Bidwell inside a trunk as punishment for throwing eggs at another house. When Mary found out, she tried to let Bidwell out, but Sam attacked her, forcing her to bludgeon him to death with a fireplace poker. She then let Bidwell out and had him help her bury Sam at a property belonging to her father-in-law. The incident warped Bidwell's mind ever since, and he began abusing Mary and Sandra repeatedly. Mary called police on two separate occasions to get Bidwell kicked out of the house, but she later dropped the charges on both occasions. On May 9, 2011, Bidwell was scheduled to marry a wealthy woman, Sharlene Taylor, but the wedding was called off after she suddenly married another man. Afterwards, Mary and Sandra never saw Bidwell again.
When Bidwell started committing a series of annual abductions and tortures of young boys, the BAU is eventually pointed to Mary's direction by Sandra. During the drive to Mary's house, Hotch, JJ, and Rossi learn that Sam is nowhere to be found. Upon reaching Mary's home, they greet her at her doorway and ask about her son. When they tell her of their suspicions on Bidwell, Mary dismisses the claims, states that Sandra is being a bit dramatic, and tells them about how Sharlene broke Bidwell's heart. She then adds that Bidwell is a good person and that he isn't capable of committing his crimes. However, the agents tell her that they know about Bidwell's past and that what she is doing isn't the best way to keep him safe. Eventually, however, Rossi is able to convince Mary to reveal what she had done to Sam. When she confesses, JJ assures her that she committed the killing in self-defense and that she was protecting herself and her children.
Under the BAU's prodding, Mary reveals where she buried Sam's body. Bidwell is tracked down at the property, arrested, and interrogated inside the house. However, he proves to be uncooperative, forcing JJ to bring Mary in as a last resort. Her presence surprises Bidwell, but he regains his composure. When she begs him to reveal where Hunter is, Bidwell refuses. Mary scolds him, telling him what he is doing is wrong and that Hunter is just like him when he was a boy. She then apologizes for not ending the abuse sooner and begs him to help Hunter, saying that she already made things bad and that he shouldn't make them any worse. Touched, Bidwell reveals the location of the box, and Hunter is rescued in time. Bidwell is then taken into a police cruiser, but not before Mary hugs him goodbye. As they watch the car take him away, Mary is consoled by Hotch, who says that she can't keep blaming herself for her son's actions.
- October 31, 2002: Sam Bidwell (her husband; fatally bludgened with a fireplace poker in self-defense)