Boy, 17, jailed for murder after strangling his sister and stabbing her multiple times because she was ‘annoying’

A 17-year-old boy has been jailed for the brutal murder of his ‘annoying’ older sister.

Mali Bennett-Smith fatally stabbed his older sister, 19-year-old Luka Bennett-Smith, at the home they shared on Cromwell Road in Bristol on 20 October 2024.

Bristol Crown Court heard that his sister had agreed Bennett-Smith could practise a headlock on her, but instead of letting go when she tapped him, as he had done on previous occasions, he continued to hold her before stabbing her repeatedly.

The murderer was sentenced to a minimum term of detention of 10 years and five months after pleading guilty to her murder on Monday. 

The two siblings had been home alone in the St Andrews area of the city when the killing took place, with the brother, who had attention deficit hyperactivity disorder, initially watching a video upstairs. 

Mali Bennett-Smith told police: ‘After watching a video, I went downstairs to the lounge and I asked Luka if I could practise a headlock on her.

‘She agreed, we have done this before and when she needed me to stop we had an agreement where she would tap me on the arm.

‘On this occasion I had decided I was not going to stop, I wanted to kill her, I had enough with regards she had been treating me over the years and recently.’

Pictures of the crime scene at Cromwell Road following the murder on 20 October 2024

Twenty minutes after the killing he dialled 999 and said: ‘I stabbed my sister to death.

The court heard that he told operators they had not been having an argument, but he said: ‘I hated her my whole life and I don’t know, I just didn’t want to ever see her again.’

Judge William Hart said today at Bristol Crown Court: ‘It’s often said in courtrooms when a child has died: ‘It must be every parent’s worst nightmare’.

‘The horror of the loss of their daughter at the hands of the son they still love is beyond even the worst nightmares.’

The court heard that Bennett-Smith grew up on a remote farm in New Zealand, where he was home-schooled, but after his parents divorced he moved to the UK with his sister and mother with the aim of going to college to prepare to join the Army.

He later dropped out of his college course, the court was told. 

Sentencing him to detention during his majesty’s pleasure, the judge said: ‘The killing was shocking and brutal.

‘It has deprived Luka of her life, your parents in effect of two of their children, and will deprive you of your liberty.’

Forensic investigators pictured at the scene where the girls body was found at 6:30pm on October 20

Mali and Luka Bennett-Smith lived together at a home on Cromwell Road in the St Andrew’s area of Bristol

He said the use of a knife, the fact Bennett-Smith ‘undoubtedly intended to kill’ and the brutality were aggravating features.

He added: ‘The scene that met the paramedics on arrival at that house will, I imagine, live with them forever.’

Ray Tully KC, defending, said Bennett-Smith has severe dyslexia and dysgraphia and, although he has an above average IQ, was found to have below average ‘processing speed’.

He said the teenager’s ‘somewhat unconventional’ upbringing meant he did not mix with other children his own age, and spent a lot of time gaming.

Mr Tully said the defendant would disappear into a world of video gaming and become dissociated from the real world.

He said: ‘Mali did not know how to manage his increasing feelings of frustration and resentment towards Luka.’

He said the teenager, of Cromwell Road, had ‘genuine remorse’ for his actions.

The judge lifted reporting restrictions on naming the defendant after an application by the PA news agency.

After the sentencing, Detective Inspector Nadine Partridge of Avon and Somerset Police said: ‘Our thoughts remain fully with Luka’s family at this difficult time. They continue to be updated and supported by specially trained family liaison officers.’