A man had marks on his hand which could have occurred the night he allegedly killed his teenage sister.

A doctor on Wednesday agreed with the suggestion the abrasions on Connor Gibson may have come from "punching something".

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.

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Jurors heard how Gibson was examined by forensic medical examiner Dr Shona Anderson at a police station two days after the alleged killing.

Prosecutor Richard Goddard KC took the witness through marks she had found on Gibson's body that night.

Among the findings, Mr Goddard put to her at one stage: "Connor Gibson had abrasions over the knuckles of his hand when examined?"

The doctor agreed.

The advocate depute also asked would the marks "be in keeping" as having possibly occurred on the Friday.

Dr Anderson said: "These injuries could have occurred on the Friday night."

Mr Goddard asked: "This could have been caused by a number of different mechanisms?"

She replied: "Yes."

The prosecutor asked: "Could have been caused by punching something?"

Dr Anderson said: "Yes, it could have been caused by that mechanism."

The trial went on to hear of a number of phones recovered during the police probe and what was on them.

A black Samsung mobile was examined having been found at the Blue Triangle housing project on November 28 2021.

Jurors have previously heard how Gibson had been staying there at the time of Amber's disappearance.

Police cyber crime team leader Peter Benson analysed the device.

He found a Snapchat user called 'Connor' had messaged a group chat at 12.34am and 10 seconds on November 27 2021.

The text read: "I am really going to need you guys help with something when you guys come back. I am being serious."

Around 40 seconds later, the person called 'Connor' messaged Amber asking: "Are you OK?"

Mr Goddard asked Mr Benson: "Was there any sign that the message was ever read by the user Amber Gibson?"

The witness: "No, all I can tell is that it was not read by the recipient."

The trial has previously heard Amber was reported missing at 2am that morning.

Mr Benson also found a web search on the phone dated around 11.30pm on November 27 stating: "How to get nosy police officers to stop monitoring your phone."

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 has lodged a special defence of alibi.

The trial, before judge Lord Mulholland, continues.