‘Who Killed Deon?’ was designed to help tackle youth violence by educating disenfranchised teenagers about a legal principle known as joint enterprise. The idea was an interactive murder mystery hosted on Facebook, a ‘whodunnit’ about a boy called Deon. It embraced a teenage audience by enlisting them as co-creators and collaborators. The campaign was 4.5 times more efficient than budgeted, but its intention was also to prevent young people entering a life of crime in the future. It is predicted the campaign will generate a payback of £8.50 for every £1 spent