A man accused of murdering four people during a drug-fuelled rampage across Darwin claimed voices told him to harm himself, a court has been told.
Benjamin Glenn Hoffmann has pleaded not guilty to four counts of murder on June 4, 2019, saying he'd been poisoned and it had caused him to be "out of his mind".
Psychiatrist Robert Parker examined the 47-year-old in police custody soon after the four men were shot dead in less than an hour at four locations.
During the interview, Prof Parker asked Hoffmann if he'd experienced any hallucinations or if voices were telling him to perform actions, to which he replied "no".
But in the weeks after, Hoffmann reported during two further assessments that he was hearing a male prison guard's voice, which was directing him to self-harm.
"Even though I look healthy, I feel like my mind is f***ed," Hoffmann was reported to have said, according to notes taken at the examination.
He also said he'd been hearing his mother's voice and was reading the Bible in his cell, Prof Parker told the Northern Territory Supreme Court on Thursday.
"He reports he is confused ... if his thoughts are really his own," he said reading from his medical notes.
Prof Parker came to the conclusion Hoffmann wasn't suffering from psychosis and said there was no evidence he had been suffering hallucinations.
However, he said Hoffmann appeared to be struggling to adjust to prison life while he was on remand before his trial.
Earlier, Prof Parker said he concluded Hoffmann wasn't suffering from a "significant psychiatric illness" following an assessment on June 4 soon after the shootings.
"Ben was not suffering a significant disturbance of mood or psychosis or active cognitive impairment," he said.
Prof Parker also said he found no signs that Hoffmann had been poisoned as he had claimed or involuntary intoxication.
The court has heard Hoffmann, who suffers an anti-social personality disorder, was high on methamphetamine during the rampage.
Forensic physician Angela Sungalia said the drug was unlikely to have caused him to suffer a psychotic episode but it could have caused him to become paranoid, aggressive and violent.
"He became disinhibited and he was angry to the point that he acquired weapons and he searched for specific people who he believed had injured him by poisoning and who he believed had led his girlfriend astray," she said.
After the killings, Hoffmann told police he believed he'd been poisoned the night before and it had caused him to be "out of his mind" and temporarily insane.
The Crown says Hoffmann was searching for his ex-girlfriend, Kelly Collins, and a man she said she loved, Alex Deligiannis, when the killings happened.
Prosecutor Lloyd Babb SC says Hoffmann's first victim, Hassan Baydoun, was fatally shot four times at the Palms Motel in central Darwin.
Hoffman then allegedly shot Nigel Hellings through the front door at the 75-year-old's apartment block about 800m away.
The third man to die was Hoffmann's good mate, Michael Sisois.
The 57-year-old's body was found with a single gunshot wound in the car park at The Buff Club bar and restaurant.
Hoffmann is also accused of murdering Rob Courtney, 52, at an industrial yard at Darwin Recycling about 2.5km away.
Mr Deligiannis had previously visited three of the locations regularly.
The trial continues.
