Dispatches: Witness Intimidation Revealed

Knife and gun crime is on the rise but prosecutions are falling. Key witnesses are terrified of giving evidence - with good reason. Livvy Haydock explores the dark world of witness intimidation, and finds a sophisticated and highly effective system of menacing violence amplified and driven by social media. She meets the gangsters who threaten 'stitches for snitches' and families of witnesses who paid the price of telling the truth in court