A FULL DNA profile for Angus Sinclair, the man on trial for the World's End murders, was obtained from within knots tied in one of the victims' bras, which had been used as part of a ligature to strangle her, a jury was told.

The High Court at Livingston heard it was 20 million times more likely the DNA came from a combination of Sinclair and his late brother-in-law Gordon Hamilton than from either of them acting alone or from neither of them.

On the 13th day of the trial of Sinclair, 69, the jury heard a second full day of detailed evidence from forensic scientist Geraldine Davidson.

She took them through DNA evidence found on the clothing of Christine Eadie, who was murdered with her friend Helen Scott in October 1977. They were both 17.

In the majority of cases, the samples yielded partial mixed profiles, with Hamilton and ­Christine herself the major contributors. But components matching the relevant parts of Sinclair's profile were also found in the ligatures used to bind and kill Christine.

Ms Davidson told the jury there had been particular interest in the knotted areas of the tights and bra used as ligatures on Christine, as the knots would "preserve" the DNA present at the time they were tied.

She added: "This fits with the DNA within the preserved areas having been present at the time the ligatures were tied."

In the case of Christine's bra, recovered with part of her tights from around her head and neck, Ms Davidson said specialist analysis had been carried out. This confirmed Hamilton had been the major contributor of DNA within the knots.

But although Sinclair had been the minor contributor in terms of the amount of material left on the ligature, he was "fully represented".

She added: "It's a full profile. Some of the components of his DNA are shared with the other three reference samples [Hamilton and both victims], but every one of the components of Angus Sinclair's profile are represented in the profile."

She said statistical analysis of the results, carried out by Professor David Balding, who had given evidence earlier in the week, had established Hamilton had been a billion times more likely to be the major contributor to the DNA in knots on the bra than any unrelated person.

In addition, he had found it was 20 million times more likely that both Sinclair and Hamilton had contributed DNA to the mix rather than only one or neither of them.

Hamilton's DNA on the relevant parts of the bra had come from semen. In Sinclair's case, because there had been less material it was not clear whether the source of his DNA had been semen or "cellular material".

Ms Davidson said: "Had Angus Sinclair and/or Gordon Hamilton used the very ligature to bind and strangle Christine Eadie, you would expect to detect their DNA on the surfaces of the ligature."

The Lord Advocate, Frank Mulholland QC, prosecuting, repeated her conclusion back to her slowly as a question.

She replied: "You would expect to find their DNA."

Sinclair denies acting with Hamilton in raping, battering and murdering Christine and Helen 37 years ago.

The girls were last seen leaving the World's End pub in High Street, Edinburgh, on the night of October 15, 1977. Their bodies were found four miles apart in East Lothian next day.

Sinclair has lodged three special defences: incriminating Hamilton for the murders; claiming consent to any sexual activity; and alibi claiming he was fishing at the time of the murders.

Ms Davidson resumes her evidence today, with the focus on Helen's clothing.