Simply thinking about such things is enough to send shivers of terror into our hearts. Even the words are dark and scary.
We all like to imagine that we are safe, that the world is a rational and reasonable place. But who knows what the person standing next to you is really capable of…?
And, if pushed, how far would you go to protect someone you love - or punish someone you hate?
True crime stories show how easy it is for normal people to find themselves in a situation of utter despair or utter madness. Crime is not rational and there's only so far you can go to protect yourself. The people in these stories are just unlucky. Some are tricked or trapped by the evil intentions of others. Some are simply in the wrong place at the wrong time.
As we go about our daily lives, shopping, working and meeting friends - crime is the fear that we all share. But we should take comfort in the fact that violent crimes - however terrible they may be - are still incredibly rare.
These real-life crime stories were taken from the pages of the top UK weekly Real People magazine.