Where does this urge come from, and why is so powerful? If we all experienced this urge, would we be able to resist?

Is would it genetic, hormonal, biological, or cultural conditioning? Do serial killers have any control over their desires? We all experience rage and inappropriate sexual instincts, yet we have some sort of internal cage that keeps our inner monsters locked up. Call it morality or social programming, these internal blockades have long since been trampled down in the psychopathic killer. Not only have they let loose the monster within, they are virtual slaves to its beastly appetites. What sets them apart?

Then in March, 2004, BTK sent a very convincing letter to the local newspaper, taking responsibility for the September, 1986, unsolved death of Vicki Wegerle. Included with the letter were a photocopy of Wegerle's driver's license and three photos of her body that BTK took after he killed her.

In May, BTK sent a copy of the chapter titles of David Lohr's Crime Library story on the case to a local TV station. Lohr's feature story was the only BTK case history on the Net at that time. However, BTK had changed several of the chapter titles, including one that he changed to "Will There Be More?"

And so, it began again, with BTK impatiently pointing out to police the murders of his that they missed. Finally, BTK made the mistake that culminated in his capture.

Here is the most detailed story of this case as it unfolded in 1974 and then again in 2004.

Eventually she was allowed to do household chores such as cooking, washing dishes, and cleaning up for the couple and their two children. Yet whenever Cameron yelled "Attention!" she was to strip off her clothes, stand on her tiptoes, and reach her hands to the top of the doorway between the living room and dining room.

Then one day the whole nightmare ended as quickly as it had begun.

Famed former FBI profiler John Douglas had been asked by police to look into Hansen as a suspect. He took note of the fact that Hansen was of small stature, heavily pockmarked and suffered from a severe speech impediment. Due to Hansen's unsightly looks, Douglas surmised that he suffered from severe skin problems as an adolescent and was probably teased by his peers. In turn, he would have low self-esteem, which would have prompted him to live in an isolated area. Douglas considered the abuse of prostitutes a way for perpetrators to get back at women.

The mother of the first victim saw Jones kneeling at the foot of her daughters grave, sobbing and wailing the child's name over and over. She rocked back and forth, apparently in deep anguish, as if Chelsea had been her own daughter.

This extraordinary murderer killed by decapitation unique in the annals of serial killing but then, he was a surgeon by training, brought down by alcoholism and drug addiction, and knew the human anatomy like the back of his hand. Reduced to eating out of garbage cans after his surgical career was over, he took out his anger on the human refuse that lived in the industrial wasteland of Kingsbury Run.

Once a loving little girl, she grew up around and, from a young age, worked in slaughterhouses. Her most cherished possession was a set of razor sharp boning knives, which she kept in pride of place above her bed. Given her future violence, is fair to say that this period in her life played a major role in the molding of the monster that she would become.

But even today, the many visitors to Aberdeen's murder house still ponder how a middle-aged housewife, mother and grandmother could perpetrate such evil.

When McCafferty, called the Australian Charles Manson, was set to be released in 1997 after being imprisoned 23 years, the people of Australia were outraged. Since McCafferty was not an Australian citizen was exported back to his native Scotland, where he continued to be a problem.

Her whole demeanor made her easy to ignore. A lackluster young woman, blank unblinking eyes behind nondescript spectacles, she seemed to be the kind of person who wandered around the fringes of life, always overlooked. Perhaps she had issues with her father. She certainly had seemed a little odd when she first walked into police headquarters claiming that her father had turned her into his sex slave.

Her tale was one of imaginable depravity. She talked of how her father, a bookish churchman, had raped her when she was just 13. Her will had been totally subjected to his. By the time she was finished talking, Agnes had implicated herself and her father in the murders of five family members.

The body parts that would later be pulled from the mud in Pandy's murky basement, the slabs of unidentified "meat" pulled from his freezer, would offer an even more chilling glimpse into the horror.

Burakov then embarked on a cat-and-mouse game with Russia's worst serial killer. Once he suspected Andrei Chikatilo, a former teacher, he placed him in a cell with a gifted informant, hoping that Chikatilo would slip up. By law, he could only hold him for 10 days. On the 9th day, he tried something daring: he brought in a brilliant psychiatrist.

Renee was 25, blonde, and independent. She spoke three languages and had a bright future, with the aim of getting a Ph.D. in French literature. Sagawa asked her to teach him German, and since his father was quite wealthy he could pay her well. She accepted.

He found these Nordic women overpowering, and even as he claimed he loved them, he wanted to posses and destroy them and so he did. He lured her to his home to murder and eat her to satisfy his long-held sexual fantasy. Avoiding prison for his crime, the cannibal is now a celebrity in Japan.

To understand the horrific saga of Australias worst serial killing case, one must first go back in time. Back to a foreboding 1994 prequel: a grisly find at rural Lower Light, about 50 kilometres north of Adelaide, the South Australian capital.

And no one knew why.

Long before Freddie Krueger or Jack the Ripper, theater-goers have been thrilled with the legendary exploits of Sweeney Todd, the murderous barber who dispatched his customers with a flick of the razor and then had his lover serve up the remains in a tasty meat pie.