A forensic scientist has told a court it is "likely" that two teenage girls killed 37 years ago were tied up by different people.

The High Court in Livingston heard the bindings used on Christine Eadie "showed different knot-tying characteristics" to those used on Helen Scott.

Witness Roger Ide said the findings indicate the victims had been tied by two different people - although he explained it did not represent strong evidence to that effect.

The evidence emerged on the sixth day of the trial of Angus Sinclair, 69.

He denies raping and murdering the 17-year-olds, who were last seen at Edinburgh's World's End pub on October 15, 1977.

Sinclair is accused of carrying out the attacks along with his brother-in-law Gordon Hamilton, who is now dead.

Mr Ide, 72, now retired, prepared a report for the court in May this year after being asked to look at various ligatures used to bind the two girls.

His report, which he read out to the jury, concluded: "The bindings to Christine Eadie showed different knot-tying characteristics to those used to secure Helen Scott.

"This indicates that the two victims had been tied by two different people, but it does not provide strong evidence to this effect."

He told the court: "I've looked at many bindings to victims of different sorts over many years and you sort of recognise the handwriting, almost.

"I can't be certain but it looks to me as if Christine Eadie was tied by someone that knew a little bit more about what he was doing than Helen Scott.

"None of the knots used to secure Helen Scott were skilful at all."

Jurors have previously heard that Christine's body was found at around 2.25pm on October 16 1977 at Gosford Bay, Aberlady, and Helen's body was discovered at around 6pm that day in a field near Haddington in East Lothian.

Sinclair denies the charges against him and has submitted three special defences of incrimination -blaming his brother-in-law, now dead; alibi -saying he was fishing near Cockenzie power station at the time; and consent to sexual intercourse.