Moment two-year-old son tells of moment he witnessed mother's murder

This is the astonishing moment a two-year-old boy chatted with his father about the knife-wielding murderer who killed his mother in front of him in a London park.Rachel Nickell, 23, was stabbed 49 times on Wimbledon Common while walking her dog Molly with her son Alex on July 15, 1992 in a crime that shocked the nation.Miss Nickell was also sexually assaulted by the attacker before he fled - and Alex was found by a passer-by next to his mother, repeatedly saying: 'Wake up, Mummy.'