As a late comer to this thread I felt I would add my own 2 pence worth to the discussion.
To those who claim she has no place in a "civilised society", having read articles regarding her upbringing, it would be fair to say she is a product of a so called civilised society. She has come from a middle-class family, with a relatively easy upbringing, in a reasonably well off area of Hertfordshire.
She is a product of the "civilised society" she grew up in. A society obsessed with fame, vanity and wealth. A society that seemingly enjoys depravity, violence and the bizarre. One only has to look at the majority of popular TV programmes of late or even the coverage of cases such as this to see. Big enterprise promotes and glamorises anathemas to further their monetary gain, without a second thought for its effect on the impressionable.
As a result the impressionable begin to spiral in to a world of fantasy, seeking validation and attention to fill the void but always find themselves feeling unfulfilled (Instagram anyone?). For some, their attempts for validation and attention become more and more desperate. With the increased permeation of technology in to our everyday lives, the lines between fantasy and reality become even more blurred for those who already lack lucidity.And thus we end up with people like Joanna Dennehy.
As a society we scratch our heads, puzzled by the motivation for such things, seemingly finding no valid answers. The answers are certainly there, we are just afraid to take a look inward.