A man accused of killing his teenage sister could have been involved in an "assault" on her, jurors heard.

The conclusion was one of a number made by a forensic biologist giving evidence at the trial of Connor Gibson at the High Court in Glasgow on Tuesday.

The 20-year-old is charged with the sexual assault and murder of 16-year-old Amber Gibson at Cadzow Glen, Hamilton on Friday, November 26 2021.

READ NEXT: Man jailed for raping little girl when he was a teen

Alana Gunn was in the witness box for a second day.

She had prepared a report after swabs were taken following the discovery of Amber's body.

The court previously heard how Gibson's DNA was found on her.

Prosecutor Richard Goddard KC  took the witness through her conclusions after her analysis of Amber and other items linked to the case.

Reading from a report, Miss Gunn told the court: "In our opinion, the collective findings relating to Connor Gibson could be explained if he was involved in an assault of Amber Gibson and was also in contact with her while she was bleeding."

Among other conclusions were that Gibson had removed her jogging bottoms and further had been in contact with the teenager's bra and top.

However, Miss Gunn was "unable to determine" whether this was as a result of causing damage to the latter items and/or handling them.

She added in the report: "As we were not provided any information regarding Connor Gibson's version of events, we are unable to evaluate further."

Mr Goddard asked the witness about the "assault" and blood staining which was analysed.

He put to Miss Gunn the finding had been made due to its "distribution and appearance". The biologist agreed.

Gibson is joined in the dock by 45-year-old Stephen Corrigan.

He is accused of breach of the peace and attempting to defeat the ends of justice.

It is claimed Corrigan found Amber's body, but rather than alert police, he inappropriately touched her and then hid her remains under bushes and branches.

He had lodged a special defence of alibi.

READ NEXT: Cop commends victims of violent rapist

The court also previously heard how DNA matching the profile of Corrigan was found on Amber's body. A total of 39 samples to a varying degree were discovered.

In his conclusions on this, Miss Gunn stated in the report that this could be explained if he had been in "direct contact" with the girl while she was "unclothed".

The trial earlier heard claims Corrigan was never near the teenager.

He stated to police trace of him could be found after he may have urinated in a bush at the area some months before Amber was found.

But, Mr Goddard said given the findings that would be "simply untenable".

Miss Gunn: "We would not expect to collect any DNA from that four or five months later."

The trial, before judge Lord Mulholland, continues.