A JUDGE has launched a scathing attack on the Crown Office’s prosecution of Alexander Pacteau for the murder of nurse Karen Buckley.

It came as Lady Rae jailed the 21-year-old, described by experts as a “serial killer in the making”, for life at the High Court in Glasgow.

But, in highly unusual remarks, she said she could  order Pacteau to serve a minimum of only 23 years because her “hands were tied” by a Crown Office plea bargain.

Her sentence handed down yesterday means, if paroled, Pacteau could be out of prison by the age of 44.

Lady Rae was unable to impose a minimum sentence close to the maximum of 33 years because of the nature of the plea bargain with the Crown.

Pacteau clubbed to death 24-year-old Ms Buckley, a nurse and occupational therapy student from Ireland, within 20 minutes of meeting her in April this year. In the hours after Ms Buckley’s death, Pacteau went to extraordinary lengths to cover up the murder and dispose of her body, dumping her in a barrel of caustic soda.

These details were covered by a second charge of attempting to defeat the ends of justice. But this charge was dropped by the Crown under its deal to get Pacteau to plead guilty, ensuring he was jailed and a trial could be avoided.

Lady Rae, however, told the court she “regrets” the Crown Office decision adding that she could not ignore Pacteau’s actions after he killed Karen. She said she had never before been asked to “ignore significant material” put before the court.

Sources close to the police investigation and Pacteau bullishly rejected her criticism, stressing the importance of securing a guilty plea to the main charge, the murder. They said “portraying a ‘macho’ image in his statements seemed to be important to Pacteau”.

A Crown Office spokesman: “Pacteau pled guilty to the most serious of criminal charges, that of murder, which carries a mandatory life sentence. In securing the guilty plea, the Crown guaranteed his conviction at the earliest opportunity.

“The Lord Advocate ensured all of Pacteau’s relevant actions were laid before the court in a detailed narrative allowing the judge to pass what she considered to be the appropriate sentence, taking into account all of these actions as aggravating factors.”

The Crown is already facing criticism over its decision not to prosecute the driver in the George Square bin lorry crash and other motorists who have cost lives because of health problems.

However, Lady Rae said she did limit the reduction to Pacteau’s sentence, required because of his early plea.

She told him: “An important matter of law was raised at the pleading diet in August, and that was whether I am entitled to have regard to what you did after the killing in imposing sentence on the murder charge.

“I have been informed that when you first appeared in court you faced two charges, including a second alleging an attempt to defeat the ends of justice.

“The Crown, for some reason, decided not to persist in seeking a conviction on that charge, despite detailing in the agreed narrative the many factors which would have fully justified such a charge.

“The Lord Advocate submitted that I would still be entitled to have regard to what you did as an aggravating factor to the murder charge and he referred me to a number of cases which he submitted supported that approach.

“I regret that the Crown, in withdrawing charge two, has to some extent tied my hands in relation to this sentence.

“I have never known a situation in which a judge has been invited to ignore significant material in an agreed narrative deliberately put before the Court, with the consent of parties.

“After reflecting on submissions, I have come to the view that I cannot ignore your conduct after the killing.

“It has always been the position that what an accused does after a crime to conceal what he did may be an aggravating factor.”

Pacteau admitted murdering Ms Buckley last month. After killing her, he took her body back to his flat and, the following morning, he used his phone to look up information on caustic soda.

After looking up information on caustic soda on his phone the next morning, he placed Ms Buckley’s body in his bath and covered it in the corrosive material before cutting her open “to speed up decomposition”.

Pacteau, who initially denied the murder, changed his plea at the High Court in Glasgow on August 11.

Lady Rae added: “I find it extremely difficult to find words appropriate to describe the dreadful crime to which you have pleaded guilty.

“Karen Buckley was a young woman in the prime of life. In a matter of minutes, for some unknown and inexplicable reason, you destroyed her young life and devastated a family.

“Not satisfied with killing her so brutally, you went to extraordinary lengths over several days to cover up your actions by attempting to destroy her body.”

Pacteau was cleared of an attempted rape and sexual assault in 2013.