Karla Fay Tucker (AP)

Karla Fay Tucker, 23, was in the mood for acting out and she wanted to go out.  She was a tomboy who liked to prove herself in her Houston, Texas, neighborhood.  She could get into a fight with the best of them and she found good company among bikers or Vietnam vets.  In 1983, her boyfriend, Daniel Garrett, was teaching her combat maneuvers.  There's no evidence that he would have turned violent had she not goaded him into it.  She got high on speed and urged him to go with her for a ride.  She was feeling mean that night and she had a target. 

There was a guy, she said, that she disliked.  His name was Jerry Lynn Dean.  She persuaded Daniel to help her to break into his house and take something—specifically his Harley motorcycle.  Daniel did what she wanted, although he wasn't comfortable with this act.

When they entered Jerry's house in the dark, Karla heard him waking up on his futon.  Rather than leave before he discovered them, she jumped him, scaring him, and her power over him gave her an enormous rush.  He started to struggle as she straddled him, so she grabbed a pickax to hold him down, and the more he struggled, the more she was determined to keep him down.  She hit him again and again, using the ax to put 11 deep stab wounds into his throat and chest.  The bloody killing excited her and, as he died, she experienced a sexual climax. 

But that wasn't the end of it.  Jerry's girlfriend, Deborah Thornton, was there, too, so Karla began to hit her as well.  However, as Gini Graham Scott put it in Homicide, her arms got tired, so she persuaded her boyfriend to finish it.  He did what she asked.

Later she bragged about the incident to her sister, who was so disgusted she turned Karla and Daniel in to the police.  Karla was convicted of murder and executed in Texas.

Judith Ann Neelley

Like her, Judith Ann Neelley persuaded her husband, Alvin Neelley, to participate in a series of brutal crimes.  In 1980, she robbed a woman at gunpoint and then began a rampage that involved murder.  Together these two viewed themselves as outlaws, calling themselves 'Boney and Claude.'  One day they lured a 13-year-old girl into their car and in front of their own twins, they molested her and then killed her.  Judith injected her with liquid drain cleaner and then shot her.  She also shot a man, but he survived the attack and fingered her for shooting him and killing his girlfriend. 

When this team was arrested, Alvin claimed that Judith had instigated the crimes, being responsible for eight murders, and he had just gone along with her.  She liked to have power over others, he said.  He didn't know what else to do.

Yet when she was arrested, she quickly blamed Alvin and said she was a victim of domestic abuse.  She tried to claim she was insane and could not help what she had done.  While the jury convicted her of murder in 1983, they recommended a life sentence.  However, the judge sentenced her to death, but her sentence was commuted in 1999 to life in prison. 

One of their victims who had escaped said that Judith was the one with the gun, and that she had bragged about committing numerous murders, but no evidence ever linked her to any unsolved cases.  Nevertheless, she appears to have had a thirst for violence and power.  That she was young, slender and blond gave her an advantage with those who would rather believe that the male was the instigator.  She was just a girl, after all.  Yet the facts of the case say otherwise.

Not all teams are out-and-out killers.  Some escalate from other crimes.  They cross one moral boundary, and that makes it easier to cross another.