Police say they attempted to help a teenager convicted of encouraging terrorism - but he continued to create videos 'potentially radicalising others'.
Daniel Harris published far-right extremist films which are believed to have influenced at least one gunman involved in an American mass shooting.
Following his conviction it emerged the 19-year-old had been referred to police for his extreme views and put onto a deradicalisation programme, but he continued to post online.
Speaking after the sentencing, Detective Chris Brett said: "While efforts were made to support him - with a referral to establish if he had been groomed, and attempts to engage with him through the Prevent programme - the extent of his views and intentions were exposed through his continued efforts to post and create online content of an extreme nature throughout."
Manchester Crown Court heard the teen, from Glossop in the Peak District, had previous convictions including the racially aggravated criminal damage of a memorial to George Floyd in Manchester.
He was engaged with a deradicalisation programme, but told the operative his behaviour was a “blip” - denying having any interest in politics.
At the time he made those claims, the court heard, he was creating a video homage to Thomas Mair, who murdered MP Jo Cox.
Judge Patrick Field KC said Harris demonstrated “a level of deceit and cunning”.
Detective Brett spoke of Harris' "continued efforts to post and create online content of an extreme nature throughout".
He said: "Harris could see the reaction his videos were getting. This was not a one-off, this was not a game, this was a concerted effort to generate a following and influence people."
"Even once arrested, Harris continued to be obstructive to our investigatory efforts."
Harris began producing the extreme far-right videos from his granddad's spare room aged just 17, celebrating armed uprisings and mass shootings.
Manchester Crown Court was told videos Harris produced were shared online by Payton Gendron, who has pleaded guilty to a mass shooting at a supermarket in Buffalo, New York.
They were also linked to Anderson Lee Aldrich, the only suspect in a shooting at a gay bar in Colorado.
Harris was found guilty following a trial of five counts of encouraging terrorism and one count of possession of material for terrorist purposes, relating to a 3D printer he was trying to use to make firearm parts.
Detective Inspector Chris Brett also said: "On the face of it Harries presents as an unassuming, quiet young man, but scratch the surface and it's a more sinister picture".
"It's no secret that across the country we are seeing more and more young people hitting the radar of counter-terrorism police, especially those who are displaying extreme right-wing views."
"Anyone who downloads, shares or creates extreme content online risks being arrested under terrorism legislation.
"And don't think you can hide behind usernames, avatars and other technical blockers, as we have teams of highly-skilled digital investigators with a track record for getting to the source.
"As we have seen in this case against Daniel Harris, such irresponsible and hateful behaviour can have deadly consequences.
"Not only did he create and share offensive posts and videos, he tried to make a gun.
"While not all individuals have the means to act upon their words, in the online space, they can easily spread to inspire others who do."
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