The man accused of carrying out a deadly mass shooting in Darwin in June 2019 will argue his defence on the grounds of mental impairment, the Northern Territory Supreme Court has heard.

Forty-six-year-old Benjamin Glenn Hoffmann is facing a series of charges, including four counts of murder, after the shooting in Darwin city last year.

In the Supreme Court this morning, Mr Hoffmann’s lawyer Jon Tippett QC was asked by Chief Justice Michael Grant if his client would “run the defence of mental impairment” and Mr Tippett replied: “Yes, Your Honour.”

In previous court hearings, Mr Hoffmann’s legal representatives have indicated he will plead not guilty.

The court also heard today that Mr Hoffmann has been approved for legal aid to fund his defence.

• Darwin shooting accused to stand trial

Mr Tippett indicated that additional “special” funding would likely be required, due to the magnitude of the case.

The trial will likely take place at the end of this year or beginning of 2021.

The court heard the prosecution case includes up to 480 potential witnesses and the trial, dates for which are yet to be set, could run for up to 12 weeks.

Crown Prosecutor Tami Grearly told the court the duration of the trial would depend on the volume of evidence.

“It will depend, in part, on how much evidence is going to need to be called in relation to the issue of mental impairment, how many psychiatrists and psychologists will need to be called,” she said.

Mr Hoffmann appeared via a video link from Darwin’s Holtze Prison and did not speak during the hearing.

He is due to return to court in July for a pre-trial hearing.

-ABC