William Buchan, 51, of Perth, who distributed child porn images online, had his prison term reduced by a third because of the mistake by prosecutors.
Proceedings were delayed for more than a year due to an oversight within the procurator fiscal’s office.
Buchan won a ruling to say that the delay in the case against him had been “unfair” and the sentencing sheriff was forced to restrict how long she jailed him for.
Sheriff Fiona Tait told Buchan – who was caught sharing hardcore child porn with other paedophiles – that she wanted to send him to prison for three years.
But she told him that because the Crown had been responsible for a serious delay in the case she would have to limit the period he spends behind bars to just 24 months.
Last night, a Crown Office spokesman confirmed that Lord Advocate Frank Mulholland, the Scottish Government’s chief legal officer, had launched a probe into the incident.
The spokesman said: “The Lord Advocate has asked for an urgent report from the procurator fiscal to address the delay in taking court proceedings.”
Sheriff Tait told Buchan at Perth Sheriff Court: “There was a delay in this matter being brought to court. The procurator fiscal depute said it was as a result of human error.
“I have taken into account these circumstances. I have had careful regard to the issue of delay. You will be sentenced to 24 months in prison. That would have been a period of three years had it not been for the delay.”
Buchan admitted distributing indecent images of children on 2 November, 2011. He also admitted two charges of having the images between August 2011 and July 2012.
Solicitor David Holmes, defending, said: “There was a period of 18 months where there was a delay. The case was first submitted in January 2013.
“Through no fault of Mr Buchan’s there is then a period from January 2013 until November 2014. It seems to be human error in operating the systems.
“Given the time taken to prosecute, it was not unreasonable for him to think nothing was going to happen. But then he was prosecuted in November 2014 – two and a half years after the search warrant was executed.”
Holmes had argued that the case against Buchan should be thrown out altogether because of the time taken to bring him to court after the initial search took place.
The court was told that Buchan downloaded child porn at various locations including his former workplace in Cumbernauld. He had hundreds of images from near the most severe end of the scale and he traded images with members of an online paedophile community.