The 33-year-old, not named for legal reasons, appeared in Wagga District Court on Thursday via video link from the Custodial Mental Health Centre at Silverwater Correctional Complex.

The man was charged with one count of wounding a person with intent to cause grievous bodily harm and one count of common assault.

The man's barrister, Christine Mendes, and Crown prosecutor Trevor Bailey agreed to apply for a special verdict of act proven but not criminally responsible under the Mental Health and Cognitive Impairment Forensic Provisions Act.

District Court Judge Gordon Lerve found beyond reasonable doubt that the man committed the two offences but found he was not criminally responsible.

"This is a very sad case," Judge Lerve said.

Judge Lerve was presented with reports from two psychiatrists, one each engaged by the defence and prosecution, that both agreed that the man suffered from drug-induced psychosis and severe and chronic treatment-resistant schizophrenia

One psychiatrist found that the man was commanded by an auditory hallucination to stab his guardian.

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The man was at his home about 7pm in September 2020 when his guardian visited to assist him with his medication.

The guardian also used an abattoir-style boning knife with a yellow handle to cut up some meat so that it could be properly stored in the fridge.

The guardian left the knife in the sink and did not see the man stab her but felt an "excruciating pain" in her back before managing to escape in her car.

A surgeon's report stated that the guardian suffered a laceration with a length of 5 centimetres on the left side of her back, a collapsed lung and penetrating injuries to her spleen and diaphragm.

The next day, a male nurse in the mental health ward of Wagga Base Hospital saw the man, who was wearing handcuffs, attempt to remove an intravenous tube.

The nurse turned to call for other staff to assist when the man placed the handcuffs around the nurse's neck and kicked him in the groin.

Police officers then attended the room and were able to separate the man from the nurse.

Judge Lerve stated he was satisfied that, on the balance of probabilities, the man was either unaware of the nature of his actions while offending or was not aware that his actions were wrongful.

The two psychiatrists told the court that the man had started using cannabis to alleviate headaches from a traumatic brain injury in 2010.

The man then proceeded to start smoking methylamphetamine, taking MDMA and abusing kerosene.

Self-harm and a motor vehicle accident in 2017 also contributed to further brain damage.

A psychiatrist reported that the man "feels very upset about what happened" but still showed disorganised thought patterns, unstable mood and poor impulse control despite nine months of treatment and abstinence from drugs following his arrest.

Judge Lerve said he was firmly of the opinion that the man should not be released after the special hearing.

The man did not visibly react when Judge Lerve read out his decision.

Under the order, he will be held at a mental health centre until a process of law determines he can be released.