A man who raped a student after dragging her into bushes has been jailed for ten years.

Alasdair McDonald was sentenced for the violent attack on 21-year-old Katie Johnston, who waived her right to anonymity, in Aberdeen.

He has also been given a three-year supervision order.

The court heard how McDonald was watching pornography in a flat and headed out to the city centre before following his victim into Union Terrace Gardens.

As she sat on a bench to text her flatmate, McDonald dragged her into bushes and trees and raped her.

Sentencing the 49-year-old, Lord Arthurson said: "Your victim was a 21-year-old university student who was entirely unknown to you.

"You had, on your own account of events to social workers, been viewing pornography within a flat and then proceeded into the city centre.

"You saw your victim walking alone and followed her along a street and down into the public gardens area below street level.

"As your victim was seated on a bench texting her flatmate, you seized hold of her neck from behind, placed your hand over her mouth and dragged her across the ground towards an area of bushes and trees.

"You forcibly removed her lower clothing, repeatedly struck her on the head, seized hold of her neck and head and restricted her breathing.

"You then restrained her and assaulted and repeatedly raped her with considerable ferocity. Your victim did not see your face, your clothing or anything of you."

The court heard that during the rape McDonald used excessive force to rip the crotch area of his victim's pants.

It was found some yards away and contained McDonald's DNA.

After the attack McDonald was initially spoken to as a potential witness and told officers: "I saw a black man walking away."

An extensive trawl of CCTV in the city centre revealed that McDonald was in the area at the time the rape was committed and DNA analysis conformed he was the rapist.

Lord Arthurson added: "To her you were a faceless, violent and predatory rapist. Indeed, such was the ferocity of your attack that the forensic physician who gave evidence at your trial advised the jury that one of the internal injuries which you inflicted upon your victim represented the most serious injury of its type which he had seen throughout all of his years of medical practice."

He continued: "On the basis of the evidence led before the jury and the material contained in the report before me, I have concluded without difficulty that you represent a high risk of causing serious sexual harm from which it is necessary to protect the public."