The case of Ayssa Bustamante, who, at the age of just 15 killed her nine-year-old neighbour in cold blood because she wanted to find out how it felt to murder someone.

The case of Mathew Hardman, dubbed the 'vampire killer', who thought that by taking a life he would become immortal. He stabbed an elderly neighbour to death, removed her heart and drank her blood.

Stephen Hough got away with raping and killing 16 year old Janet Cummings for over 40 years. He fabricated an alibi for his horrific crimes and let an innocent man go to jail, but detectives never gave up.

Teenage couple Kim Edwards and Lucas Markham, who came from troubled homes, prompting them to make a cold-blooded plan to get rid of the mum and sister Kim bitterly resented.