Detectives appeal for viewers' help in cracking some of the UK's toughest cases, including the murder of farmer Julian Gardner, who was attacked and left for dead by a gang of robbers at his Sussex farm.

Plus, five years after Yorkshire widow Nora Tait was bludgeoned to death in her own home, police renew their appeal to catch her killer. Officers leading the investigation reveal the anonymous Christmas card they received in 2009 - possibly from the killer himself, hinting at inside knowledge of the crime. Detectives urgently need viewers to identify whoever sent this card. Show less