It is said that you can't write without a reader. The opposite holds true as well; you can't read without a writer. But if as a single, creative person you are one in the same, then, well.....problem solved! Great writing is born from that which we personally long to read.
For the writer, the serial killer is, abstractly, an analogue of the imagination's caprices and amorality; the sense that, no matter the dictates and even the wishes of the conscious social self, the life or will or purpose of the imagination is incomprehensible, unpredictable.
I don't write about what I know: I write in order to find out what I know.
A human being always acts and feels and performs in accordance with what he imagines to be true about himself and his environment...For imagination sets the goal ‘picture’ which our automatic mechanism works on. We act, or fail to act, not because of ‘will,’ as is so commonly believed, but because of imagination.
The characters within a book were, from a certain point of view, identical on some fundamental level ‒ there weren't any images of them, no physical tangibility whatsoever. They were pictures in the reader's head, constructs of imagination and ideas, given shape by the writer's work and skill and the reader's imagination. Parents, of a sort.