When a 17-year-old girl was attacked and murdered in her Wiltshire home, her killer was until the day before her boyfriend. What made him turn killer? S2/Ep1
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? S1/Ep6
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? S1/Ep5
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? S1/Ep4
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? S1/Ep3
A clever child from a loving home, William Cornick shocked Britain when he stabbed to death his teacher in 2014. What caused his pathological hatred? S1/Ep1