As the episode later revealed, Beth was actually one of two wives of Roger, as shortly after Roger married Beth L. Herrixson, he also married Debbie S. Bixbey, who was pregnant with his child, a daughter named Amy. Both wives were led to believe that Roger traveled for a living, with Beth stating that she believed that Roger was with the CIA. However, Beth began to learn about Roger's other life when Roger called her "Debbie" on a couple of occasions. Beth would learn the truth after getting Roger's dirty laundry out of the trunk of the car, as she also saw materials for making a volcano (which was Timmy's science project) as well as cut out stars that she made for Timmy.
As it turned out, Amy had the exact same project made, as Beth would see when she followed Roger to Henderson two weeks prior. It was there that Beth learned that not only did Roger have another wife, he had a another family as well. Angered over being humiliated by Roger, Beth turned heel and decided to kill Roger, doing so by placing a bomb inside his rented car (a Camaro). The villainess took back her pliers that Roger borrowed from her to make both volcanoes, and used it to build the bomb, planning to have it detonate during Roger's trip to the airport. However, the timing was delayed by an hour, and by that time, the car ended up in the possession of U.S. Marshal Adam Watson, who was killed (along with two valets) by Beth's bomb.
Roger ended up suspected when it was revealed that he rented the car, but after his reveal as a bigamist, he stated that he borrowed a pair of pliers from Beth to use for Amy's volcano. His revelation that he meant to return them ended up revealing Beth as Roger's attempted killer, as the same pliers were used to fix the hose bib. In her interrogation, the evil Beth confessed to planning to kill Roger, stating that she was angry over Roger's double life and adding that he made a mockery of their marriage. In response to Gil Grissom's question regarding the use of a bomb, Beth stated that it wasn't much harder to make a bomb than it was to make a volcano, and she was arrested (off-screen) afterwards.
- Susan Diol also appeared on Diagnosis Murder as the evil Jeri Murdico.
- "I'd always suspected there was another woman, but never ... another family. So. Two weeks ago Sunday, I followed him. He, uh, dropped off his rental car and walked to some apartment building. Then he changed his clothes, and got into a nicer car, and drove out to Henderson. (Catherine: "Why didn't you just leave him? Turn him in?:) He made a fool out of me! A mockery of our life! (Catherine: "Mrs. Dunbar, you killed three innocent people.") That was never my intention. That bomb was supposed to go off at 8:30 on his way to the airport. (Grissom: "Why a bomb?") It's not much harder to make a bomb than a volcano." (Beth Dunbar revealing her motive for planning to kill her husband, Roger)