Scarlet Blake, 26, appeared at Oxford Crown Court on Monday after being found guilty last week.

Warning: This story contains descriptions that readers may find distressing

Blake live-streamed the dissection of a family pet after watching a Netflix documentary called Don't F*** With Cats, in which Luka Magnotta kills kittens before filming a murder.

Prosecutors said Blake had a "fixation with violence" and found Jorge Martin Carreno, 30, while searching the streets of Oxford looking for someone to kill in the early hours of 25 July 2021.

The body of the BMW factory worker, a Spanish national who was walking home alone after a night out with colleagues, was found in the River Cherwell at Parson's Pleasure around 24 hours later.

Judge Mr Justice Chamberlain KC described the killer, who is transgender, as having an "obsession with harm and death" as he sentenced her to a minimum term of 24 years in prison.

He told Blake: "The decision to kill was entirely yours. You were completely indifferent to this suffering."

The judge said he could not be sure of the exact method Blake used to kill Mr Martin Carreno but said the murder was "the culmination of a plan" Blake had been formulating for months.

The trial heard a murder investigation was launched two years later when Blake's former partner Ashlynn Bell, who lives in the US, told detectives she had confessed to killing Mr Martin Carreno using a homemade garrote.

Blake pleaded guilty to a charge of criminal damage over the killing of the cat, but denied murdering Mr Martin Carreno by inflicting blows to his head before trying to strangle him and then putting him in the river.

Four months before his death, she used food and a crate to capture a cat and take it to her home, where she killed it.

'Grotesque act of cruelty'

Mr Justice Chamberlain said she had carried out "a grotesque act of cruelty" by filming herself torturing the cat before killing it.

In the video, in which Blake dissects the animal, removing the fur and skin, she says: "Here we go my little friend. Oh boy, you smell like shit. I can't wait to put through the blender."

Prosecutors said it showed she had a "disturbing interest in what it would be like to harm a living creature".

"You suspended the cat by its neck, using a ligature made from ribbon," the judge said.

"But, although you strangled it, you made sure that it remained alive for at least three minutes, during which it endured intense pain."

Blake cut the animal's heart out and kept it "as a memento," the judge said. After she had killed the cat, Blake continued dissecting the animal before placing it in a blender.

She later "boasted" about her actions and spoke of "her desire to open up a person like her 'little cat friend'," the court heard.

"It was an interest that went beyond mere fantasy," Alison Morgan KC told jurors, who were also shown videos of Blake and a partner engaging in consensual strangulation with ligatures.

"She described herself to others as being someone who derived sexual gratification from the thought of violence and the thought of death," said the prosecutor.

'Jorge's life will be remembered'

Speaking shortly after the sentencing, Detective Superintendent Jon Capps condemned the murder of Mr Martin Carreno as a "barbaric and chilling act" that had been done with "total disdain for life".

He also paid tribute to Mr Martin Carreno's family for the "enormous dignity they have shown throughout this ordeal."

Det Supt Capps said: "They [the family] have put enormous faith in my team. They've had to come to terms with this not just this being a murder, but the character and nature of this defendant served to only compound the grief they feel.

"It is Jorge's life that will be remembered over and above the acts of this defendant."

He added that the jury will receive support to deal with the graphic evidence they were exposed to during the trial.

'Fixation with violence'

CCTV footage shown during the trial featured Mr Martin Carreno trying to find his way home, while Blake walked the streets, wearing a facemask and distinctive combat-style jacket with a hood over her head, while carrying a rucksack.

"He died because he encountered the defendant on that night," said Ms Morgan. "He died because he met a person who had a fixation with violence and with knowing what it would feel like to kill someone."

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Blake, who was born in China before coming to the UK aged nine, blamed Ms Bell for making her kill the cat.

She said Mr Martin Carreno was still alive when she left him at the riverbank, and that she had made up details of killing him to please her ex-partner after seeing his death in the news.

Mr Martin Carreno's family paid tribute to "an extraordinary being full of passion and kindness". He was one of three triplet brothers.

They said in a statement: "Today, his absence leaves a deep wound in our hearts. His life was stolen, cutting short his projects and dreams."

Mr Martin Carreno's mother added that her son "aspired to build a better world" and was an "incredibly good person".

It is understood Blake will serve her sentence in a men's prison.