One Evil Bitch : Joanna Dennehy

When you take a closer look at the list of the bloodiest and most violent murders throughout the history, the chances are you will mostly encounter male names. Female serial killers are incredibly rare in our society. Women are unlikely to go out on a random killing spree and injure more than one person in a cruel way. When women do kill, they prefer using poison and their motives are very personal and driven by passion. Of course, there are always exceptions to the rule like Aileen Wuornos who became the most famous female serial killer. She shot and killed seven men in Florida over the course of several years. 
You can only imagine the shock that spread through Peterborough, a small town in the eastern part of England when bodies started showing up in ditches over the course of several days. The investigators discovered that three grisly murders were committed by Joanna Dennehy. She was troubled but her life to that point only involved drugs and alcohol, at least to those who didn't know her well. Something happened and she simply snapped, going on a killing spree that frightened the entire Cambridgeshire, as well as the rest of the Great Britain. Her erratic behavior that escalated during those two weeks while she was on a prowl continues to puzzle experts and the law enforcement to this day.