James Gargasoulas was a 26-year-old heavy drug user with an extensive criminal record when he drove a car at high speed through central Melbourne killing six people, including a baby boy and a 10-year-old girl.He was sentenced to life in prison earlier this year for the January 2017 attack. Despite a guilty verdict there are still outstanding questions about why James Gargasoulas was able to carry out such a crime.Four Corners investigates how James Gargasoulas was out roaming the suburbs of Melbourne despite facing serious criminal charges and clear warning signs that he presented a grave danger to others.