A teenager who stabbed his mum 94 times following a 'two-year diet of constant DVDs' has been jailed for at least 15 years.
Kieren Smith, 17, became 'fascinated with knives' and murdered his 42-year-old mum Leah Whittle at her home in Weymouth, Dorset, last July.
Winchester Crown Court heard that Smith attacked his mother in the flat they shared before telling police she had been killed by a group of drug-dealers to whom his brother owed a drug debt.
Smith, who has an IQ of 72 which puts him in the lowest 4 per cent of the population, was expelled from school at the age of 14 and had spent the last two years alone in his room, watching DVDs.
Jailing him for life, Judge Guy Boney described Smith's crimes as 'utterly dreadful'.
"You have been convicted of a deeply shocking and really utterly dreadful offence - that of killing your own mother in as brutal a way as can be imagined," he said.
"You have cut short by many years the life of the very person who gave you life in the first place and expressing your crime in that way tells everyone the true horror of what you did.
"Your life revolved around watching DVDs alone in your room with an absence of emotional engagement.
"It is from that diet of constant DVDs that your fascination of knives came from."
However, Judge Boney accepted that Smith's family life had been 'non-existent' and 'unfulfilling' given his parents separated when he was a baby.
He said: "I accept that you are not by nature an emotional man but you have shown not a smidgen of remorse."
Nicholas Haggan QC, defending, said Smith's motive for the killing was unknown.
"It's always difficult to give an explanation and in this particular case it's impossible," he said.
"One will never know why the defendant did what he did. This is not an ordinary case; we accept it's very unusual for a young man to kill his mother.
"He is a very lonely and unhappy individual who finds it very difficult or impossible to express his true emotions - he has told us again and again he finds it impossible to cry."
Detective Inspector Marcus Hester, of Dorset Police, said: "This case involved a particularly horrific and sustained attack on a woman who was unable to defend herself.
"This is a very tragic case where a young man, through his own violent actions, has killed his mother.
"He now has to face the consequences of these actions as well as to live with the loss of his mother."