The murder trial of a man (32) with schizophrenia has heard he believed his mother was an imposter when he attacked her at their home in Co. Kilkenny.

Niall Stapleton admits killing Siobhan Stapleton (51) at Glebe Lodge, Kilfane in Thomastown on Friday May 25th last year, but denies murder by reason of insanity.

Psychiatrist Dr. Stephen Monks from the Central Mental Hospital has been called by the defence to give evidence at the Central Criminal Court.

He says Niall Stapleton told him that he had been hearing voices in the week leading up to the attack telling him that his friends did not exist. The accused also complained that he had experienced difficulties in differentiating between what was and was not real.

Mr. Stapleton described feeling disorientation and paranoia at a family barbecue on the night before the killing. He believed his beer had been spiked with LSD.

The jury has already heard the accused was diagnosed with paranoid schizophrenia in 2008 but that he did not accept the diagnosis and had a poor history of taking his medication.

On the Tuesday before she died, Siobhan Stapleton confronted her son about not taking the anti-psychotic drugs he had been prescribed.

Multiple skull fractures

He told Dr. Monks that both his parents put pressure on him to take his medication but he believed the government wanted people to get addicted to these drugs as a money making scam.

The jury heard he did not sleep well on Thursday night and that he got up early on Friday morning and walked the dog. Niall Stapleton said that when he saw his mother Siobhan in the garage that lunchtime, for some reason he believed she was an imposter.

He said he saw the handle of a spade and felt he better take matters into his own hands.

He believed if he hit the doppelganger, it would disintegrate. He said he attacked his mother as she came out of the garage and then panicked when he realised what he had done.

The jury has heard Siobhan Stapleton was brought by ambulance to St Luke's Hospital in Kilkenny, but died later that day.

A post-mortem exam found 28 injuries - including multiple fractures of her skull and facial bones, along with lacerations and puncture wounds to her head.

The bloodied handle of a garden fork was found on the grounds of the family home. The trial continues.