AI bot told teen to use a hammer to kill his mother

For 18 years, Angela Shellis ‘fought tirelessly’ for her son Tristan.

But the ‘unbreakable’ love she felt for her deeply troubled younger boy – as well as his successful university undergraduate elder brother – was to be betrayed in the cruellest manner imaginable.

Diagnosed with autism and ADHD, Tristan Roberts spent hours a day in a toxic online world where he could give vent to his most depraved fantasies.

He was so divorced from reality – and obsessed with violence and mass murderers – that he became fixated on the notion that his ‘devoted’ mother was to blame for his unhappiness.

Fuelled by unjustified anger and poisonous misogyny, which he spouted on the controversial gamers’ messaging app Discord, Roberts began plotting to kill her.

In a chilling glimpse into the insidious power of AI, the teenager turned to the technology’s unmonitored might for tips on what kind of weapons a ‘non-experienced’ killer should use.

Then, Roberts turned 18. He didn’t spend his birthday drinking with friends. 

Instead, he visited a local branch of The Range store chain, where he bought a knife and disposable razors, showing ID to prove he was 18 – the required legal age.

The purchase concerned the cashier, who kept a copy of the teenager’s receipt. The next day he bought another knife. 

Two weeks later, he enacted his callous plot – putting his mother through a four-and-a-half-hour ordeal of unspeakable horror.

Roberts recorded every moment of it. From the initial assault to the final fatal blows. Mercifully for Angela’s family, those moments weren’t played to court. 

It was agony enough for them to hear how Roberts held his 45-year-old mother prisoner in her own bedroom, repeatedly attacking her with a hammer and strangling her. 

He then led her to a nature reserve and bludgeoned her to death with the hammer he had bought on Amazon for £20.

What could possibly have motivated such brutality? That is a question that continues to haunt Angela’s family.

Roberts, who had a fascination with serial killers, including TV series Dexter and the movie American Psycho, has offered no explanation; in police interviews he responded ‘no comment’.

In a note on his laptop a week before the killing he spelt out his twisted desire for ‘vengeance’ against his mother, saying he was ‘Not Tristan Roberts, but Alex’.

Self-pityingly he described his ‘entire life’ as ‘a s***show of f****** hell, just hell, abandonment, betrayal, bullied, nearly froze to death, physical effort, suffering’.

‘All of it and most caused by one person, and not myself.

‘And now that one person, not out of sadistic pleasure or malice, but out of revenge, justice, vengeance and… to move forwards in life, I must take the weight off my back. 

‘Even if it hurts. There is no use living anymore if I don’t do this. I am already dead.’

In notes he wrote before the murder he said he was motivated by ‘hatred of women’. One Discord post read: ‘I do hate girls are you OK with that?’

The platform has been accused in the US of harbouring radical communities including white supremacist far-Right groups. 

Conservative activist Charlie Kirk’s suspected assassin, Tyler Robinson, is also reported to have been active on the site.

In reality, Roberts’ ungrateful and self-centred attitude was a cruel and insulting inversion of the lifelong sacrifices Ms Shellis had made for both her sons.

Her devotion to her boys is clear from her own social media accounts, peppered with pictures of them. 

‘Home is where my boys are,’ reads one post. ‘I will never understand how some parents live every day knowing they have a child out there they rarely bother about and just get on with their life without a care in the world.’

After separating from the boys’ father, she had moved back from Bedfordshire to the seaside town of Prestatyn in her native North Wales so they could benefit from the support of relatives.

A qualified teacher, described by relatives as having ‘a heart full of love and kindness’, Angela took a lower-paid job as a teaching assistant at Rhyl High School so she could spend more time with her sons. That Roberts needed help was clear.

In childhood, he was referred to Children and Adolescent Mental Health Services. He attended mainstream schools but ‘struggled’ and had a history of disruptive behaviour.

But while he was diagnosed with autism and ADHD, to this day, professionals have detected no recognised mental health disorder – relatives now suspect he ‘manipulated’ doctors.

Adolescence was turbulent: he spent time in hospital, in homeless accommodation and a period with his father in Milton Keynes. 

What support Angela sought – and with what, the court heard, ‘limited success’ – will doubtless become clearer with time. 

Denbighshire County Council said yesterday that it and ‘partner organisations’ had referred the case to North Wales Safeguarding Board and could not comment.

What is known is that the mother and son relationship became ‘strained’. Family members, too, were worried about Roberts’ deteriorating behaviour after the family moved to Prestatyn.

In February 2025 he was given a six-month referral order by Llandudno youth court for possession of a bladed item in a public place and shoplifting. 

Neighbours reported him behaving aggressively towards them, and overheard him shouting in the family’s semi-detached house.

It is a devastating feature of this case that both Angela and her elder son, Ethan, had begun to suspect the threat Roberts represented towards her. 

As Mold Crown Court was told, on October 17 – four days after Roberts had turned 18 – the worried mother messaged a social worker and friends, stating that he had bought a knife and a hammer.

In one note on her phone she asked: ‘Why?? What does he need these for? Is he planning to hurt me, himself, what? Who? Why? FFS.’ 

Ethan too was concerned; before going back to university, he set up wireless-enabled cameras inside the family home. 

But unknown to either of them, Roberts’ plans were escalating.

In the early hours of October 18, he posted messages on Discord stating that he had been standing over his mother holding a hammer as she slept but did not use it.

The next morning, she wrote a note on her phone reading: ‘OMG… I did not sleep well at all… and Tristan kept coming into my room too – why? Am I safe in my room tonight?’ 

Meanwhile, Roberts’ posts on Discord were becoming ever more disturbing. 

In one chat he boasted about being able to chop a bear apart with a weapon. 

Another said: ‘She is gonna just vanish off the earth. I already tried everything else. Now it’s time.’

In a third he wrote: ‘I can kill her bare-handed. I only want to make it brutal and make sure I don’t mess up with an axe.’

His accounts were repeatedly taken down for violating the platform’s policies against abusive and threatening content and his posts deleted. 

But Roberts, who wasn’t in education, kept thousands of screenshots (recovered by police after the murder) and simply set up new user names – a total of 16 different accounts.

In the weeks running up to the murder he used Chinese AI search tool DeepSeek to ask for tips for a ‘non-experienced killer’, including whether he should use a knife or a hammer. 

After it refused to engage, Roberts tricked it by lying that he was writing a book about serial killers.

Once Ethan had gone back to university for the new term, Roberts put his murderous plan into practice. 

Along with weapons, he bought a balaclava, facemasks, overalls and clingfilm.

His mother was particularly vulnerable because she was off work and using crutches due to a leg injury. 

On the evening of October 23, he made a brief voice recording in which he said that he was ‘Alex’ – believed to be his murderous alter ego – and was going to kill his mother. 

The attack began at around 11pm and lasted until 3.30am. ‘This is the moment we are doing it,’ he said. ‘We are going to hit her with a sledgehammer.’

Ms Shellis was conscious before pleading in a ‘calm and firm voice’ for him to phone 999 for medical help. 

She even offered to ‘back him up and say that he had not known what he was doing’, prosecutor Andrew Thomas KC said.

But, preying on her devotion, Roberts convinced her to leave the house, under the pretence she could have her injuries treated.

He ordered her to put on a balaclava – to restrict how far her blood was spread, police suspect – then tricked her into taking a ‘short cut’ through a nature reserve. 

There, he took the sledgehammer out of his rucksack and rained down blows on her, leaving her to die.

He returned home alone at 5.35am and was filmed on a doorbell camera leaving again 50 minutes later, swinging a carrier bag thought to have contained bleach to clean the murder scene. 

He was thwarted by the presence of dog walkers and he returned home.

Later that morning he logged straight back on to Discord, writing: ‘I’ve just had the craziest day.’ 

He said that he had ‘beat the s***’ out of his mother, and described how he had ‘smashed her skull’. 

Angela’s body was found just after 8.30am, but it took police several hours to establish her identity.

Relatives were worried and tried to contact her – but Roberts sent messages from her phone to say she was laid up with a ‘bad throat’.

Ethan sent his mother’s phone a message asking: ‘Just call me for a second… so that I know you are alive.’ 

Roberts – posing as their mother – replied: ‘I think I am alive [laughing emoji]’.

When he was arrested later that day, he had barricaded himself into his bedroom. He calmly asked officers: ‘Is the body you found my mother?’ 

The murder weapon – a £20 ‘mini sledgehammer’ bought on Amazon – was seized at the home.

As he was given a life sentence yesterday, devastated relatives were still struggling to comprehend the tragedy. 

In a powerful victim impact statement to the court, Ethan said their mother had done anything and everything for Roberts ‘his whole life’.

‘Mum never gave up on him. I don’t know how he could do this to anyone, let alone the one person… that would do absolutely anything for him,’ he said.

He felt ‘haunted’ by anger as well as guilt that he was unable to protect his mother.

Her sister, Sarah Gunther, said she wanted her sister to be remembered as ‘a mum who never gave up, no matter what life threw at her’. 

Addressing her nephew directly, she told him how the family ‘fought so hard to try and get you the help you needed’.