A 17-year-old stabbed his grandmother to death out of a deluded fear that she would kill him or cause him serious harm, a jury was told.
Consultant forensic psychiatrist Peter Misch said that Pietro Addis, who is now 19, was suffering from a paranoid psychosis when he killed Brighton restaurant boss Sue Addis, 69.
Dr Misch told the jury at Lewes Crown Court today (Wednesday 22 February) that the psychosis was transient and that Pietro Addis recovered without medical treatment.
He said that Sue Addis, who ran Donatello and Pinocchio, had been concerned enough about her grandson’s behaviour to seek help. She researched whether he might need to be admitted to a mental hospital.
Mrs Addis had played a big part in Pietro Addis’s life after the boy’s mother died from cancer when he was nine years old, the court was told.
And Mrs Addis had previously taken him to see a paediatrician who diagnosed ADHD (attention deficit hyperactivity disorder) and prescribed Elvanse, an amphetamine.
Pietro Addis, of Radinden Manor Road, Hove, admits manslaughter after killing his grandmother at her home in Cedars Gardens, Brighton, in January 2021.
But the teenager, who was a catering student at the Greater Brighton Metropolitan College, denies murder and is being tried by a jury of four men and eight women.
He admitted manslaughter on the ground of diminished responsibility because he was suffering from paranoid psychosis.
Dr Misch said that there were a number of social and neurodevelopmental factors, adding: “He was taking prescribed medication and he was misusing substances. That is another factor that has to be considered in the mix.”
He said that the psychosis was not induced by cannabis or other drugs but added: “Drugs and the misuse of drugs were significant in the background of this case.”
And he said that Pietro Addis’s paranoid psychotic belief at the time of the killing was “that his grandmother was going to kill him or cause him serious harm”.
Dr Misch added that the teenager’s abnormal mental functioning had undermined his ability to form a rational belief.
Over the previous months, the jury heard that Pietro Addis had become withdrawn and isolated and the teenager told Dr Misch that he had lost his friends during the coronavirus lockdowns.
In one interview with Dr Misch, he said that Pietro Addis was reluctant to answer questions about what had happened when he killed his grandmother because it was “emotionally traumatic for him”.
When Dr Misch asked Pietro Addis if he knew why he was being held on remand, the teenager said: “For committing a murder.”
Asked who, he said that he had killed his grandmother – and, he said: “It was bad.”
Asked why, he told the psychiatrist: “I don’t have an explanation.”
He hadn’t planned to kill Mrs Addis but, Dr Misch said, “in his words, things had built up” after Christmas.
Dr Misch told the jury that Pietro Addis had said to him: “My Nan was looking at knives and then looking at me.”
On the day of the killing, he had returned to her home and they had spent time in the kitchen and watching the television.
Pietro Addis said: “When I came back, she was being weird – staring, standing, not nice. The TV kept moving around.
“My Nan went into the kitchen and she was holding knives. She was going to do me harm. She left the knives. I took them.”
When Dr Misch asked about the stabbing shortly afterwards, Pietro Addis said: “I don’t want to talk any more.”
Before the killing, he said that he had been “up all night for a solid week”.
Although Pietro Addis had admitted previously smoking up to two cannabis joints a day, Dr Misch said: “He denied using any drugs or medication prior to the killing.
“He hadn’t voices but he had ‘seen animals’ prior to the killing.”
The visions had included spiders and geckos and Pietro Addis told the psychiatrist that he had been paranoid: “I thought that people were out to get me.
“She was out to get me … I don’t want to speak about it. I was under threat … the night before, my door was opening and closing because of my Nan.
“I felt that she was threatening my life … I don’t want to talk about it.”
Dr Misch said that the teenager was regretful about what he had done – and was disappointed and angry that he didn’t get the help he needed before the killing.
What was he thinking when he killed his grandmother? Dr Misch said that Pietro Addis had told him: “I was just scared. I wasn’t thinking. It just didn’t seem real.”
The psychiatrist said: “He was deluded at the time. He was fearful.
“His disorder was so profound, so impairing, that he couldn’t take responsibility for what he did.
“There were other factors going on. He was taking drugs – both legal and illegal. He was withdrawing from drugs.”
Tomorrow (Thursday 23 February) Dr Misch is due to cross-examined by Rossano Scamardella, for the prosecution.
An argument for not legalising cannabis.