A man has gone on trial accused of trying to murder his grandmother while she prepared lunch for him just a few days before Christmas 2013.

Eoghan O’Mahoney of Craigford Drive, Killester, Dublin 5 claims he attacked her after hearing “voices” commanding him to kill her.

On the morning of Dec 19th 2013, Eoghan O’Mahoney returned to his home at Killester in Dublin after taking his then 88-year-old grandmother to get a flu jab.

She told Gardai she was preparing lunch for them at her own house across the road when he appeared with a 6 inch kitchen knife and attacked her.

Another grandson, Eoghan’s brother Conor, came to her rescue after unexpectedly calling into the house.

During Garda interviews, Eoghan kept saying he’d no choice but to kill his grandmother. He said he “loved her to bits” but had received a “vision from God” and had taken a “lifetime to plan it”.

A psychiatric expert diagnosed him with schizoaffective disorder, which is a severe mental illness that can cause delusions and hallucinations.

The jury will soon be left to decide whether special verdict of Not Guilty by Reason of Insanity applies in the 34-year-old’s case.