Mother Angela Vane's panic after 'strangling and stabbing her two-year-old son' Angela Vane, 40, admitted killing son Shaun, two, at family home in Devon Vane found by passerby on wrong side of safety barrier at bypass Mother-of-three suffers with paranoid schizophrenia, court told Appeared at Plymouth Crown Court via video link from psychiatric unit A mother who admitted strangling her toddler son and stabbing him to death has been detained indefinitely in a psychiatric unit. Angela Vane, 40, who suffers with paranoid schizophrenia, strangled her two-year-old son Shaun O'Neill with a neck tie before fatally stabbing him in the abdomen at the family home in Devon. A court heard mother-of-three Vane told a passerby who found her standing on a bypass on the morning of Shaun's death: 'I've just killed my baby.' 'An unimaginably sad case': Shaun O'Neill, two, left, was strangled and stabbed to death by his mother, Angela Vane, 40, who admitted manslaughter at Plymouth Crown Court yesterday Vane denied murder but pleaded guilty to manslaughter on the grounds of diminished responsibility at Plymouth Crown Court yesterday. She was discovered at around 8am on January 19 on the wrong side of a safety barrier on a bypass near her home in Modbury, Devon. Vane told the man she was going to jump as she had just killed her son. She told him: 'I'm in a lot of trouble, I've just killed my baby.' The passerby took Vane to the local police station, where she admitted the offence. Police officers searching the family home discovered Shaun dead on his mother's bed. He was discovered with a neck tie bound tightly around his neck and a stab wound to his abdomen, the court heard. Medical reports later confirmed he had been killed by ligature strangulation and a stab wound to the abdomen. Manslaughter: Vane is being detained indefinitely at a psychiatric unit after she pleaded guilty to manslaughter at Plymouth Crown Court Vane, who has two children in their 20s from a previous relationship, told police officers she had tried to strangle her little boy. She said: 'It went on for ages. I thought if I put a knife into him I could feel his heart. Vane appeared in court via a video link from Fromeside Clinic in Bristol yesterday. Sentencing, Judge Graham Cottle described the case as 'unimaginably sad' and said Vane was 'very unwell' at the time of Shaun's death. He said it was his responsibility to detain Vane under the Mental Health Act due to the risk she posed to both herself and the public. 'This is an unimaginably sad case,' he said. 'It's quite clear that you were clearly very unwell at the time when you took your child's life. Nobody has any criticism of you as a mother, in fact the contrary is true. You have two older children whose response to this has been both compassionate and understanding. You were clearly unwell. You were suffering from paranoid schizophrenia and the nature of your illness and the degree of it as such requires you to be detailed in hospital. That is the most appropriate disposal of the case. Defending Vane, Fiona Elder said prior to the incident there had been no criticism of the mother and that Shaun had been a 'well-cared for child'. The court heard how Vane, who separated from Shaun's father in 2010, has a history of mental illness. She was admitted to the Glenbourne mental health unit in Plymouth in 2011 where she spent three weeks being treated for acute psychosis, during which Sean was taken into care. The police were called to the family home on numerous occasions prior to her being sectioned as Vane suffered with delusions and thought Mr O'Neill was spying on her and shining laser beams on her home, the court was told. Speaking after the sentencing, Detective Inspector John Ardron, of Devon and Cornwall Police, said: 'This is a case where there are no winners. It is one of the saddest and most tragic cases I've dealt with in 24 years.'