Teen Asked AI About ‘Better Weapon for Murder’ — Held Mother Captive for Hours Before Killing Her With a Sledgehammer

An 18-year-old man from Prestatyn, Wales, has been jailed for killing his mother after researching weapons online, including asking an artificial intelligence (AI) chatbot about “a better weapon for murder.”

Tristan Roberts killed his mother, Angela Shellis, 45, with a hammer on October 24, 2025, after holding her captive inside their home for more than four hours. Prosecutors said he had purchased weapons and protective clothing weeks in advance, indicating the attack was planned.

The body of the 45-year-old teaching assistant was found in undergrowth by a member of the public at Morfa Nature Park.

A murder investigation was launched by North Wales Police, and Roberts, of Coniston Drive, was identified as a suspect. He was taken into custody and charged with murder following four days of questioning.

Investigators said Roberts held Shellis captive inside their home for more than four hours before the attack. During that time, he allegedly assaulted his mom and refused to allow her to leave her bedroom.

In the recordings he made during the attack, Shellis pleaded with her son to call 999, North Wales Live reported.

CCTV footage captured the pair leaving their residence on foot shortly before 3:20 a.m. After reaching the park, Roberts allegedly used a hammer to kill his mother.

Roberts was later seen on camera walking home alone, before returning to the park area, where he attempted to clean the murder scene.

Roberts appeared at Mold Crown Court on February 5 and pleaded guilty.

On March 5, he was sentenced to life imprisonment, with a minimum term of 22 and a half years.

Senior Investigating Officer Andrew Gibson said, “Within hours of Angela’s body being discovered, Tristan Roberts was identified and arrested. While in custody, he was charged with Angela’s murder.”

He continued, “Through a thorough investigation, the Major Incident Team, supported by specialist teams, were able to piece together the final hours of Angela’s life, as well as evidence the extent that Tristan Roberts had gone to, over several weeks, as he planned to kill his mother.”

Gibson thanked the Prestatyn community for its assistance during the investigation. “I would like to finish with a thought for Angela, who showed tremendous bravery on that fateful night, who remained calm and continued to show her caring nature and love she had for Tristan, despite what must have been a terrifying ordeal for her,” he said.

“It was important that Angela remained the focal point throughout the investigation, and I hope today’s sentencing allows for some closure and supports Angela’s family in moving forward and towards rebuilding their lives,” he said.

Angela’s sister, Sarah Gunther, said: “I pay tribute to my beloved sister, Angela — a woman whose heart, strength, and spirit shaped the lives of everyone who knew her.

“She had so many amazing qualities, but one of the greatest was the way she devoted herself to her boys. She was a fantastic and fiercely supportive mum, the kind who never gave up, no matter how hard life became. She fought tirelessly for them, and her love for them was unbreakable, a source of strength that carried her and her boys through every challenge.”

She continued, “As we move forward, let us carry her light with us. Let us honour her by remembering the joy she brought, the kindness she showed, and the courage she lived with. Angela may be gone from our sight, but she will never be gone from our hearts. Her echo will remain in every story we tell, every smile she inspires, and every moment we feel her presence guiding us still.”