TEENAGER Lewis Dale has said he "does not deserve to be on this planet" after stabbing his grandparents.
He told Hull Crown Court he can't remember attacking Irene, 78, and Allan, 80, as they were lying in bed. Irene died at the scene of the attack at their home in Summergangs Road, east Hull, while Allan was seriously injured.
He admits stabbing them, but denies murder and attempted murder, claiming he was suffering from a psychotic episode brought on by using M-Cat.
When asked how he felt about killing his grandmother, he held his hands to his face and sobbed.
"I feel like I don't deserve to be on this planet," he said.
"I know it wasn't me as a person who could do a thing like that."
Dale, 17, told the jury he was 'scared' because he was having hallucinations about a SWAT team outside the window as he was sitting in his grandparents' living room.
Dale said: "I was scared, I didn't know what was going to happen. I didn't know what they were going to do to me."
He said he remembers sitting on the sofa sharpening knives in the moments before the attack, but cannot recall stabbing them.
The court heard he went to their bedroom armed with a kitchen knife and two knives and a carving fork on his dressing gown pocket.
He had been taking the former legal high M-Cat.
He said: "All I can remember after that is throwing the knife and hearing screaming. It was a female voice."
Dale admitted he is responsible for the attacks, which he said had left him "devastated".
He described Irene as "great, unbelievable" adding: "I loved her."
Dale had earlier broken down in tears as he described how his mother died from cancer shortly before he started at South Holderness Technology College.
After that, he said, his behaviour went "down and down and down" and he was later expelled.
