A cat killer obsessed with violence and death has been jailed for life with a minimum of 24 years after being convicted of murdering a man she deliberately targeted as part of a sexual fantasy.

Scarlet Blake, 26, targeted Jorge Martin Carreno, 30, as he walked home from a night out in Oxford in July 2021.

Blake, who is a transgender woman, led him to a secluded riverbank where he was hit on the back of the head with a vodka bottle, strangled and then pushed into the River Cherwell, where he drowned.

Sentencing Blake on Monday at Oxford crown court, Mr Justice Chamberlain said: “Your decision to kill Jorge was not a reaction to something he had said or done. It was not a momentary mistake. It was not a decision made in anger, or because your emotions overcame you. It was the culmination of a plan you had been considering and formulating for months.”

The judge said that there was no evidence of sexual activity at the scene of the murder but there was “ample evidence [Blake] derived sexual gratification from strangulation”.

Listing aggravating factors, the judge said: “There was therefore a clear sexual motivation for the killing. You also believe that you would derive pleasure, whether sexual or not, from the experience of killing a person. I am sure that you did derive pleasure from killing Jorge as you had from killing the cat.”

Prosecutors said Blake killed Carreno, a BMW worker, because she had a “fixation with violence and with knowing what it would be like to kill someone”.

During her evidence, she claimed she had a fragmented personality, which included being a cat, and miaowed at the jury to show how she would interact with friends.

The murder came four months after Blake livestreamed the horrific killing of her neighbour’s cat. Blake used cat food and a carrier to lure the pet. Setting up a tripod and camera, she suspended the cat with a ribbon, before cutting it open.

After the killing, Blake dissected the animal, decapitated it, removed its fur and skin, and placed its body in a blender.

Once she had dissected the cat, she said: “Well, one day, I want to learn how to do this to a person.”

During the video, the New Order song True Faith played in the background, which the court heard was in homage to a Netflix documentary called Don’t F**k with Cats about a man who killed felines and murdered a human.

During the sentencing, the judge told Blake she had an “obsession with harm and death”.

“You attributed your morbid interests to a split or dissociative personality using the language of psychiatry or psychoanalysis,” the judge said. “You talked about the difficulties you had had since transitioning in childhood, to live as a woman, and about your troubled relationship with your parents.

“All of this was part of an elaborate attempt to rationalise what you had done and shift responsibility to others. There is no evidence that you suffer from any relevant mental illness or other mental disorder. What you did is not the fault of a society that didn’t accept you. It is not the fault of your parents.”

For murder, Blake was sentenced to life in prison with a minimum term of 24 years, less 196 days already spent in custody on remand. She was sentenced concurrently to four months for causing suffering to an animal and two months for criminal damage.

Carreno was described by his brothers and parents as “someone who radiated kindness and humour and spread joy with his wit and contagious curiosity”.

He had been out with co-workers in Oxford city centre and was trying to get home when Blake found him sitting in the street.

She was seen on CCTV walking the streets of Oxford wearing a heavy military-style hooded jacket, face mask and carrying a rucksack.

Prosecutors suggested Blake was carrying a “murder kit” in her rucksack, including a garotte and leopard-print dressing gown cord, which she rejected. Giving evidence, Blake denied she was looking for a victim and instead had gone for a walk because she could not sleep.

She said she walked with Carreno to an area called Parson’s Pleasure at the riverside and left him there alive to go home, telling the jury she did not know how he died.

Suggestions that Carreno, an electrical engineering graduate, may have killed himself were rejected by his friends and by a Home Office pathologist who said he did not believe the Spanish national died accidentally.

Prosecutors said Blake had an “extreme interest in death and in harm” and got sexual gratification from violence and killings.

During the trial, jurors were shown a disturbing video of Blake consensually tying a ligature around her then partner’s neck from behind and pulling it tight until she appeared to fall unconscious.

The trial heard that Blake, who was previously known as Alice Wang, came to the UK from China aged nine, and came out to her parents as transgender at the age of 12.

The court also heard that Blake had developed an online relationship with Ashlynn Bell, a trans woman who lives in the US.

The court heard Blake confessed to Bell, who told jurors she is also sexually stimulated by violence, that she had killed Carreno with a homemade garotte before throwing his body in the water.