A teenage girl killed in 1977 may have walked in the field where her body was discovered, a murder trial has heard.

The High Court in Livingston was told of "strong evidence" that Helen Scott had probably stood or walked in the East Lothian wheat field where she was found dead.

A soil expert reached the conclusion after analysing debris taken from the victim's feet, jurors heard.

Professor Lorna Dawson was giving evidence on the seventh day of the trial of 69-year-old Angus Sinclair.

He denies raping and murdering Helen and her friend Christine Eadie, both 17, who were last seen at Edinburgh's World's End pub on October 15, 1977.

Christine's body was found at around 2.25pm on October 16, 1977, at Gosford Bay, Aberlady, while Helen's body was discovered at around 6pm that day in a field near Haddington.

Forensic soil scientist Professor Dawson told how she analysed samples taken from Helen's feet, as well as soil samples taken from the field in 1977 and this year.

She said "the soles of Scott's feet had come into contact with a wheat field" and that her feet had picked up debris "consistent with having come from a grassy environment".

From her analysis, she concluded there was "strong evidence that Helen Scott had likely stood or walked in the wheat field".

Sinclair denies the charges and has submitted three special defences.

The trial continues.