A teenager who stabbed and killed his grandmother had thought she was “going to kill me”, a court heard.

A murder trial into the death of restaurateur Sue Addis heard that Pietro Addis was suffering from paranoid psychosis when he stabbed her 17 times, according to one psychiatrist.

Dr Peter Misch, a forensic psychiatrist, told the jury at Lewes Crown Court that he believed Addis, then 17, had an impaired ability to form a rational judgement when he killed his grandmother at her home.

During an interview in custody, Addis, who is now 19, is reported to have said: “I thought she was going to kill me.”

The Argus: Pietro Addis, right, was arrested on suspicion of murderPietro Addis, right, was arrested on suspicion of murder (Image: Sussex Police)

Describing the day of the killing, he said: “My nan went into the kitchen, she was holding knives. She meant to do me harm.

“She left the knives, I took them.”

Dr Misch said: “Pietro’s abnormal mental function, including the belief that his grandmother would harm him, impaired his ability to form a rational judgement and impaired his self-control.”

The psychiatrist added that Addis had said he did not know what he was trying to do when he stabbed his grandmother.

Addis is accused of murdering his grandmother at her home in Cedar Gardens in Brighton.

He admits killing her and has pleaded guilty to manslaughter but denies murder.

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Dr Misch told the court that in another interview with Addis, the teenager said he “didn’t have an explanation” for killing his grandmother, adding: “It was bad.”

During the third day of the trial, the court heard Addis had told his father he believed he was being followed and that people were talking about him.

After killing his grandmother, Addis was transferred from a young offenders' institution to be treated at a secure hospital.

Mrs Addis, 69, was found dead in her bathroom on January 7, 2021.

 

The Argus: Sue Addis, left, was found dead in her bathroom in January, 2021.Sue Addis, left, was found dead in her bathroom in January, 2021.

Mrs Addis was a popular Brighton restaurateur who ran Donatello in The Lanes and Pinocchio in New Road She was described as a "warm and generous person" who always believed her grandson would "turn things around".

The trial, presided over by Judge Christine Laing KC, continues and is expected to last two weeks.