Britain's Deadliest Kids, Kim Edwards/Lucas Markham

A clever child from a loving home, William Cornick shocked Britain when he stabbed his teacher to death in 2014. What caused his pathological hatred?

In 2009, teenager Lorraine Thorpe, and her accomplice killed two people. Was Britain's youngest double female killer always destined to kill?

15-year-old James Fairweather terrorised a local community with random deadly attacks that left two people dead. What made him carry out such brutal murders?

Teen lovers Kim Edwards and Lucas Markham were convicted of murdering her mum, Elizabeth, and younger sister, Katie in April 2016. What led them to kill?

16-year-old Joshua Davies was sentenced to 14 years in jail for the murder of his on-off girlfriend. Why did he kill - and only confess to it in prison?

In 2013, Sean McHugh, went to a laundrette in Anfield, Liverpool to do his washing, only to be stabbed by a teenage gang. What made them kill an innocent man?