The recent shootings of two Manchester policewomen have highlighted Britain's problem with violent crime. Now a previously-discredited weapon is being used to try to fight the most serious and organised crime - the supergrass, criminals prepared to turn on their own and give evidence in court.

Panorama investigates the remarkable deals that these often violent gangsters are being offered to become the next generation of supergrasses. The agreements have led to gunmen getting off life sentences. A teenage gang member has also escaped prosecution, despite helping to cover up a fatal shooting. And Panorama reveals cases where the credibility of the supergrass is already in question. Show less