Helpless Dr Hounsome repeatedly asked “why?” and the boy could only respond with “sorry”.Mr Hounsome had several defensive wounds and his front door key was found underneath his body.Ms Maylin said the boy said he started hearing voices about a year before but never told anyone about it.Over time the voices – which adopted the accent of an Eastern European man – became “more manic, aggressive and demanding”, escalating from telling him to kill animals to carrying out attacks on random people, the court heard.She told the court the boy said: “Something in my head kept telling me to do it. I didn’t want to do it.”I tried to push myself away but I ended up doing it. I’m so sorry.”Sentencing him to a hospital order under the Mental Health Act, Mr Justice Neil Garnham said: “You killed him in the course of a vicious and ferocious attack.”The evidence suggests you are riven with remorse for what you have done.”I have no doubt that you were at the time of the attack, and that you remain, highly dangerous.”Without medication there’s a real risk of a similar event in the future.” A psychotic Army cadet “brutally” killed a university lecturer because of voices in his head, a court heard.The 17-year-old, who cannot be named for legal reasons, has been detained in a psychiatric hospital indefinitely for the “sustained and prolonged attack” against Dr Barry Hounsome, who he murdered in his home in Gosport, Hampshire, in October last year.The 54-year-old academic, who previously worked at Southampton and Bangor universities, researched dementia and Parkinson’s disease.The teenager was due to stand trial for murder on Wednesday at Winchester Crown Court.But the prosecution instead accepted a guilty plea to manslaughter by diminished responsibility after he was diagnosed with psychosis and schizophrenia.Kerry Maylin, prosecuting, told the court: “This was a sustained and prolonged attack. He said voices in his head had been telling him to kill.”The night before the incident the voice was telling him to kill someone and that morning, it was Barry.”During the attack Mr Hounsome – who lived with his Russian wife Natalia, a senior lecturer in global health economics at Brighton and Sussex Medical School – tried to escape but the boy “pulled him back and forced him to the floor”, the court heard.Gruesome details of the attack were revealed for the first time in court yesterday, including the fact the teenager stabbed Dr Hounsome 35 times and cracked his skull open before drilling his “exposed” brain. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.