Joanna Yeates's final steps recreated in hunt for killer

The film, for the BBC's Crimewatch, tracks the 25-year-old leaving the Bristol Ram pub at 8pm on December 17 before stopping at a Waitrose, Tesco and Bargain Booze, then heading home to her flat in the Clifton area. It will be broadcast at 9pm next Wednesday.

As filming was under way last night, police confirmed the murdered landscape architect had not eaten the pizza she was seen buying in Tesco. Avon and Somerset Police said tests had concluded she had not eaten the mozzarella, tomato and pesto pizza before she was killed.

The force has following more than 1,800 lines of inquiry but key evidence including Miss Yeates's sock and the pizza have not been found. Detectives are also still working to trace a light-coloured 4x4.

Yesterday Miss Yeates's parents made their first appeal since their daughter's body was found on Christmas Day in Longland Lane, in Failand, North Somerset.

David Yeates, 63, and his 58-year-old wife Theresa asked: "Do you know someone who has been, somehow, justifying her being killed? Please help us identify the killer. Jo was probably acquainted with her killer."