Auckland's District Health Board "doesn't appear to want to take any responsibility" for the release of a patient who brutally killed a man just three days later, a court has heard.

For the past week-and-a-half, Gabriel Hikari Yad-Elohim has been on trial for the murder of Michael David Mulholland in the High Court at Auckland.

Mulholland's body was found in the stairwell at the Western Springs flats where the 69-year-old lived on September 26 last year.

He was beaten to death by Yad-Elohim, a 30-year-old with a history of schizophrenia.

The Crown has suggested the killing came after a bad drug deal.

A third person, transgender woman Tai Hona Uru, had intended to con and steal from Yad-Elohim, the court has heard. But Mulholland, who has no gang ties, had no drugs to offer when Yad-Elohim knocked on his apartment door.

The defence team, led by Annabel Cresswell, argues Yad-Elohim was legally insane at the time of the attack, having been discharged from ADHB's acute mental health unit, Te Whetu Tawera, just three days earlier.

"Te Whetu don't appear to want to take any responsibility for that release," Cresswell said during her closing address today.

"You must wonder whether this underpins the whole trial and the Crown's approach."

Several questions were asked of Dr Peter (William) McColl, the service clinical director, about his decision to release Yad-Elohim.

But the doctor stood by his decision and said it was a "good discharge" from a clinic which had run out of bed space.

Medical evidence heard during the trial suggests Yad-Elohim suffers from religious delusions and was hearing the voices of God and Satan.

He had changed his name from Yuuki Watanabe to his Hebrew name, which translated means "hand or messenger of God" and believed during the court process that the jury represented the 12 tribes of Israel.

One voice was telling him he had a "divine endorsement" to kill, psychiatrist Dr James Cavney said.

The court has heard Yad-Elohim, who saw himself as a Japanese anime character, also had a conversation with the spirit of Mulholland shortly after the attack.

And after his arrest, when interviewed by police, Yad-Elohim appears to raise his glass of water to a spirit in the room.

The court heard today Yad-Elohim was born in South Korea, but identifies as Japanese and claims to have been born in Tokyo.

Crown prosecutor Kirsten Lummis, however, said Te Whetu Tawera was not on trial.

"It is a very sad indictment on our community that we have just the 56 beds available for our acute mental health [patients] ... but this is not what this trial is about, it's about what happened in that stairwell," she said during her closing address.

Last week, an external review also came to light about the treatment given to Yad-Elohim, when he was a patient at Te Whetu Tawera.

The review, which was not been disclosed to the court or lawyers involved in the trial, showed the medical notes kept on Yad-Elohim were "misleading".

However, Lummis told the jury, the review was largely irrelevant and the Crown's case was a simple one with Yad-Elohim motivated by revenge.

"It is what you see is what you get - it was a drug deal gone horribly wrong."

She said Yad-Elohim was "living the life of a drug user craving their next fix".

"This is crazy misguided offending, but Mr Yad-Elohim is not legally insane. He knew very well what he was doing was both morally wrong, and legally wrong. He was swindled, he was doing a drug deal that was a secret drug deal.

Lummis said the jury may find it "puzzling and even difficult to understand" but the CCTV footage, which filmed the entirety of the attack, showed exactly what happened.

"It's there in colour for us to see, but it is disturbing."

Lummis also said police failings after Yad-Elohim's arrest were a result of cops acting in a "highly charged situation" after having seen the video footage.

Detective Ray Fa'aofo continued to interview Yad-Elohim despite the accused's request for a lawyer and during a later exchange, Detective Ruth Niu did not read Yad-Elohim his rights before asking him a question.

Yad-Elohim has been in the care of the Mason Clinic, Auckland's regional forensic psychiatry services unit, since shortly after his arrest.

Justice Gerard van Bohemen will give his closing address tomorrow before the jury retires to consider its verdict.