The self-confessed gunman, who went on a killing spree across Darwin in 2019, is reportedly struggling with compulsive talking and organising his thoughts.
"Very recently, Mr Hoffmann was at serious risk of self-harm, he was suicidal again," Patricia Petersen, who is acting for Hoffmann on a pro-bono basis after Legal Aid withdrew its funding, told AAP on Friday.
"However, the main concern now with respect to Mr Hoffmann, especially given final sentencing is on 25 July, are his difficulties listening to, understanding and responding appropriately to relevant legal questions."
Dr Petersen described the 48-year-old's speech as "pressured, urgent and disorganised" and a "word salad".
"He jumps from one subject to another. It is very difficult at the moment," she said.
This is making it difficult for her to gather information necessary for sentencing submissions to Justice John Burns.
Dr Petersen wants the authorities to reassess Hoffmann's mental health so he can be provided with treatment if needed.
"He is obviously mentally unwell and although the medication he is currently taking may be the right medication, and necessary, it is clearly not sufficient," she said.
Mr Hoffmann is facing life in prison without parole after he pleaded guilty mid-trial in November to intentionally killing Hassan Baydoun, 33, Michael Sisois, 57, and Rob Courtney, 52 and the manslaughter of 75-year-old Nigel Hellings.
Sentencing submissions in May heard he was using methamphetamine in the lead up to the killings, and was likely delusional and suffering drug-induced psychosis when he went on the rampage armed with a shotgun.
His former lawyer, Bruce Levet, raised concerns in the Supreme Court in Darwin in March that Hoffmann was unfit to properly instruct a lawyer ahead of his sentencing.
He said Hoffmann believed an outlaw motorcycle gang, his previous legal team, the Crown prosecution team and the judge that heard his trial had conspired against him.
Hoffmann told the court in April that he was being given 410mg of anti-psychotic medication per day "for voice and visions".
His case will return to the Supreme Court in Darwin on July 25 for further sentencing submissions.
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