Crime and the crime writer

In the past there has been the occasional report of a killer citing a novel as his inspiration, but it is very rare. I seem to remember that Agatha Christie included a death by poisoning with thallium in one of her books and a later murderer said he had got the information he needed from it. Even if that's true, it can only have been the type of poison the killer took from the novel.

Fiction cannot make anyone violent. Frustration, whether sexual, financial, social, professional or emotional, usually provides the impulse to kill, and there are all kinds of reasons why some people are unable to resist it. Alcohol and drugs are involved in a lot of violent crime; brain damage may sometimes have a part to play, as may abuse in childhood, poor parenting (or even no parenting), a variety of other physical and emotional stresses, or even, if the latest research is to be believed, a diet lacking vitamins and essential fatty acids.

The other question is harder to answer. I think it is possible that crime novelists have added to the general fear of crime, although again real crime reported on screen and in print seems more likely to cause trouble.