by Maxine McArthur and Tristan-Stewart Robertson

“WHY did you do that?” shouted Paige Doherty’s aunt, lunging forward to the glass as murderer John Leathem was led down to the cells to begin his life sentence.

Judge Lady Rae could find no explanation for why Leathem would launch such an unprovoked and sustained attack on a 15-year-old girl.

His defence agent, Ian Duguid QC, offered no explanation.

Psychiatrist and clinical psychologist reports could find no mental trigger to offer some lesson to wider society to prevent another such tragedy.

Paige’s family and friends are left with a life sentence without the popular child and no reason why they’ll never see her face again.

At the High Court in Glasgow yesterday, the atmosphere was tense awaiting the punishment of Leathem after he pleaded guilty last month to Paige’s murder and attempting to defeat the ends of justice.

As friends of the family and members of the public waited outside, the heavy police presence updated them on when the case would begin and there were immediate shouts of concern for mum Pamela Munro that she would be informed.

The closest family was led in separately to the packed South Court to hear Mr Duguid offer some explanation. There was none.

Since June, two expert medical reports were prepared on Leathem and “the information is almost consistent to the point of being unable to attribute this violent attack to anything in Mr Leathem’s background,” said Mr Duguid.

“He is an unexceptional individual,” he said. There were some “obsessional” traits in Leather’s attention to detail, said the reports, but insufficient evidence to diagnose a personality disorder. There was no evidence of anger management problems.

“No history that this is an individual who has anger management issues who is likely to explode in response to a comment he found threatening,” said Mr Duguid.

Despite Leathem having no background as a manager, he opened the Delicious Deli in Fleming Avenue, Whitecrook, and Mr Duguid said he had “pride in his work and in his own personal family”.

“So it’s almost inexplicable how these events could have come to this particular individual on the day,” he said.

“I’m sure every court is looking for something in the character of the individual that might indicate propensity for violence of this behaviour. Nobody could have possibly anticipated this outcome. There really is no explanation which could be identified to explain why he acted in this way.”

When Leathem pleaded last month, Mr Duguid offered the explanation that Paige had asked about a job at the deli on the morning of March 19. And when Leathem said she was too young at 15, Paige threatened to say Leathem touched her, then he lashed out in fear of being branded a sex offender – a slight change from Leathem’s previous defence of him offering Paige the opportunity to interview for the position and her threatening him after he said her had other people to interview.

But his own lawyer said yesterday there was no way to prove that – the claims are “unsubstantiated and uncorroborated as there is only one person who is able to say... and that is Mr Leathem”.

Lady Rae, who continued to interject through Mr Duguid’s statements, prodded to see if there was a more convincing explanation for the attack, one that left “gaping” wounds in Paige’s body because of the savagery.

“It almost defies reasonable explanation,” added Mr Duguid. “He is described as having a pleasure and pride in living in the community where his shop was located.”

He had always admitted his guilt once he was arrested, said Mr Duguid, but advocate depute Ian McSporran, prosecuting, disputed this, pointing to Leathem’s high-profile claims to the media when Paige was reported missing that she came in for a roll and then left. Instead, she was in the boot of his car and he later dumped her body two days later for passing dog-walkers along Great Western Road to find.

There was a brief discussion about the CCTV inside the shop, which was switched off, but Mr Duguid said this was anytime Leathem was working instead of his staff, not an indication of premeditation.

Lady Rae left the bench for a brief period and then returned to deliver a 1,000-word statement condemning Leathem and sentencing him to life.

She rejected his supposed excuse for the murder and cover-up: “No evidence has been placed before me to support your assertion. It is not part of the agreed narrative. It is not accepted by the Crown. A proof in mitigation was offered to you but not accepted.

“However, having regard to your Counsel’s stance that, even if your assertions were true, your reaction to that alleged threat was in no way mitigatory of this appalling, wicked crime, I need not, nor can I, make any finding on this issue. Accordingly, in my view, no evidence of any motive has been put before me to explain the ferocity of this attack.

“You must have struck the victim in excess of 146 times with a knife which, on your account, just happened to be handy in the back room of your shop. These were not just stab wounds but they included many slashing type injuries. This number of injuries excludes the separate, repeated blows which must have been delivered to inflict the large gaping wound on her neck which ultimately led to her bleeding to death.

“What you did was truly reprehensible. It is impossible to comprehend how an apparently happily married man with a young child and who is running a successful business is capable of such a horrific level of violence.

“From the victim impact statements, you have left a family heartbroken and bereft. I cannot, in this short sentence statement, do justice to the sentiments expressed by the child’s family and have thus not attempted to summarise them, but it is clear they are all understandably devastated and their lives will never again be the same after what you did.”

She jailed Leathem for life, with a minimum sentence of 27 years before he can apply for parole, reduced by three years because he pleaded guilty early.

As he was led away, the public gallery erupted with shouts of “scum” and other invectives directed to the killer.

Outside court, Pamela, with husband Andy at her side and Paige’s family and friends around her, said: “Today we see a monster put behind bars for the unthinkable, brutal crime he committed against our daughter, Paige - a beautiful 15-year-old with a full life ahead of her and a massive family and friends who are left to carry on with her no longer here.

“There is no sentence high enough to justify what has happened but we can now say there’s one less evil man in this world, which then makes the world that bit safer for our kids to grow up in.

“Paige is now safe and can rest in peace knowing justice has been served to a high standard.

“We would like to thank the public for the support over the last seven months, without this support we might very nearly have gave up but reading comments and hearing some touching words gave us the strength to carry on.

“All we can do as a family is take each day at a time.

“There is a huge piece missing in our family, it can never be replaced.”