Shelf stacker Robert McCulloch stabbed his victim to death in an aisle of a Sainsbury’s store after the pair earlier clashed at their workplace.

A judge at the High Court in Edinburgh yesterday ordered that McCulloch should serve at least 10 years and nine months in prison for the killing of Russian-born Roman Romasov.

Lord Brodie told McCulloch, who suffers from an obsessive-compulsive personality disorder, that he had psychological traits which may explain his behaviour, but did not excuse it.

The judge said: “He assaulted you in the supermarket toilet and I accept you believed your life was in danger.”

“Your victim was unarmed and you went and deliberately armed yourself with a kitchen knife and stabbed Mr Romasov with it.”

Lord Brodie praised staff at the store in Aberdeen who tried to prevent the attack and said they had shown intelligence and courage.

A manager rugby tackled McCulloch, 35, in a bid to stop him but the killer managed to free his hands and repeatedly knifed Mr Romasov.

Police called to the scene at Berryden Road, in Aberdeen, initially charged McCulloch with attempted murder and he replied: “What, you mean I didn’t do it properly?”

Mr Romasov, 28, died despite efforts to rescuscitate him following the attack.

McCulloch, formerly of Farmer’s Hall, in Aberdeen, earlier admitted murdering his victim by repeatedly stabbing him on the body with a knife on April 16 this year at the store.

McCulloch told police that he had earlier had a “fall out” with Mr Romasov. He said: “He was knocking stuff about in the shop and I told him to work properly and he started miscalling me.”

McCulloch said the victim later deliberately sat beside him at a tea break and the two men rowed. He went to the toilet and claimed Mr Romasov attacked him and grabbed him and said if he lost his job he would kill him.

He went on to tell detectives: “After that I told a couple of people about it and I was just off ma head and I was looking at the knives and I went and done it. I ran up to him and I told him he was finished and I stabbed him.

“He turned and tried to get away and I done it a few times and people were trying to stop me.”

Mr Romasov, of Tanfield Walk, in Aberdeen, died from multiple stab wounds to the chest and stomach. One of the wounds to the chest would have proved fatal alone.

Advocate-depute Alex Prentice QC said the victim had come to Britain in 2004 and moved to Aberdeen three years later. As well as working as a shelf stacker he was also studying mechanical engineering.

The prosecutor said he was described as “a very private person” who did not socialise, but was a hard worker.

Mr Prentice said McCulloch and Mr Romasov frequently worked the same night shifts at the supermarket filling shelves.

He said of McCulloch: “He took particular care with his work but occasionally his attitude would create issues with his colleagues.”

The advocate-depute said that several days before the fatal attack the two men got into a heated row at work.

He said: “It seems that the argument started because the deceased, while working, dropped crates onto the floor and the accused did not like the way in which the deceased was going about his work.”

Mr Prentice said McCulloch, who suffers from epilepsy, was later seen by psychiatrists and was assessed as sane and fit to plead.

But a psychologist said he had an obsessive-compulsive personality disorder characterised by perfectionism, orderliness and control.

Defence counsel Jack Davidson QC said McCulloch was driven by a strong work ethic and had been told he was to be promoted to a staff trainer.

“The part played in the commission of this offence by his attitude to his work is of significance,” he said.

“He took enormous pride in his work and was very zealous in its proper execution.

“When, in his view, others fell short of his high standards he had no difficulty in drawing their attention to the fact,” he said.