Judge Mark Lucraft, KC, said: “Gustavson, on the evidence you are very much the mastermind behind this grisly and gruesome enterprise. The business set up was busy and lucrative.

He said that Gustavson had “recruited like-minded people” for the “large scale, dangerous and extremely disturbing enterprise”. “The environments were far from sterile and performed by people without medical qualifications.”

Lucraft said Gustavson and his six co-defendants were motivated by “a mix of sexual gratification as well as financial reward” and described the Norwegian’s actions as “human butchery”.

“Consent is not a defence to what took place” and many of the victims “may well face life-long issues,” he added. Six of Marius’ co-defendants, none of whom have any medical qualifications, were also sentenced at the Old Bailey.

David Carruthers, Janus Atkin, Peter Wates, and Ion Valentin Ciucur, were sentenced for conspiracy to cause grievous bodily harm with intent. In addition, two further co-defendants, Ashley Williams and Stefan Scharf, were sentenced for causing grievous bodily harm with intent.

David Carruthers, 61, a former hospital porter, was jailed for 11 years after helping remove the testicles of four men.

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Janus Atkin, 39, a former “academically brilliant” veterinary science student at Liverpool and Bristol universities, was jailed for 12 years after helping remove the testicles of three men and severing the penis of another.

Peter Wates, 67, a former member of the Royal Society of Chemists and gemstone expert, was jailed for 12 years for helping mutilate seven men. Wates had been spared jail previously after officers found a “significant” quantity of ammunition at the home he shared with his father in Surrey in February 2022.

Forensic officers also discovered a pair of human testicles kept in a Flora butter-spread box marked “‘Bolete’ mushrooms” with the instruction “do not defrost”.

Wates is the former head of The Gemmological Association of Great Britain whose work was once cited by the Victoria and Albert Museum.

Ion Ciucur, 30, a Romanian national who worked at a hotel in Gretna Green in Scotland helped Gustavson sexually torture one man and clamp the testicles of another. He was jailed for five years and eight months.

Ashley Williams, 32, Carruther’s husband who worked alongside him at a passport office in Wales, was jailed for four years and six months for helping remove Atkin’s testicles with the aid of Gustavson.

Stefan Scharf, 61, a German national was arrested at Heathrow Airport while trying to fly home to Frankfurt. He was also jailed for four years and six months after helping Gustavson remove the testicle of one victim.

Scharf was also said to have been involved in the body modification scene in Germany.

The Old Bailey heard previously Gustavson had a history of “dishonest offending” in his native Norway having received two suspended jail sentences for fraud.

Prosecutor Kate Mulholland said: “Marius Gustavson ignored the risks of performing unnecessary surgery on vulnerable men for sexual gratification and financial gain.

“He actively recruited participants through his website and was paid to stream the footage of these barbaric procedures.

“Whilst the victims in this case all seemingly consented to surgeries and amputations, the victim who bravely reported his assault to the police expressed serious regret regarding his procedure and the lasting impact it has had upon him. This clearly emphasises why such practices are unlawful.

“The severity of today’s sentence should act as a warning to others that performing extreme body modifications is against the law and the CPS won’t hesitate to prosecute these horrendous crimes.”

The Telegraph, London

If you or someone you know is in need of support contact the National Sexual Assault, Domestic Family Violence Counselling Service at 1800RESPECT (1800 737 732).

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