Thomas Westwood initially claimed he had stabbed 68-year-old Susan Westwood after she threatened him with a knife at their home in Coventry on December 1 2017. The 47-year-old, who inflicted nine stab wounds using "severe" force, pleaded guilty to manslaughter on the grounds of diminished responsibility during a previous hearing at Warwick Crown Court. Opening the facts of the case against Westwood on Tuesday, prosecutor Peter Grieves-Smith QC said Westwood's claim that his mother had a knife was thought to be a symptom of his mental illness. Mr Grieves-Smith told the court Westwood asked to speak to a solicitor while on remand at HMP Hewell in Worcestershire and had expressed regret and admitted he had not acted in self-defence. Judge Andrew Lockhart QC was told Westwood, who is 6ft 3ins and weighs 18 stone, had been diagnosed with paranoid schizophrenia and autism spectrum disorder. Shortly before the killing at his one-bedroom home in Cavendish Road, Tile Hill, where Westwood slept on the sofa, he was seen outside by a neighbour in an agitated state. Westwood then dialled 999 at 8.35pm, suggesting his mother, who had mobility problems and had done all she could to support him, had wanted to slit his throat. Police and paramedics attended and the victim's body was found on a sofa as Westwood continued to claim he had acted in self-defence. The court heard Westwood, who has suffered from mental health problems since the late 1980s, told a police officer he had made his mother a cup of tea but she had threatened him because the drink "wasn't milky enough". Passing sentence over a video-link to a secure mental health unit, Judge Lockhart told Westwood that he had left his sons without a grandmother and "torn apart" his family's lives. As well as being made the subject of an indefinite hospital order, Westwood was sentenced to a 16-year prison term with an additional extended licence period of five years. The judge ruled that Westwood's condition was certainly not the sole cause of the offence but had affected his ability to control his anger. "I find as a fact that she didn't attack you with a knife," the judge told Westwood. "You told, in interviews, deliberate untruths about what your mother had done. "There is no reason at all why she would ever attack you. This case is a tragedy for all involved. "I am clear that whilst you have long-standing mental health problems, you felt great anger towards your mother - anger was the primary and driving reason why you killed her." In a statement issued by police last year, Susan's family said: "We as a family have been left devastated and heartbroken. "She was a kind, funny, generous warm loving person. To lose someone in your life is bad enough, but for Susan to be killed by someone she loved and supported endlessly is the cruellest blow."