A 45-year-old man has been charged following the shooting deaths of four people in Darwin on Tuesday.
Northern Territory Police have charged 45-year-old Ben Hoffmann with four counts of murder over this week's deadly shootings in Darwin.
Those killed were Rob Courtney, 52, Hassan Baydoun, 33, Michael Sisois, 57 and Nigel Hellings, 75, at four different locations.
Hoffmann will appear in court via video link on Friday morning charged with murder, recklessly endangering serious harm and criminal damage.
Further charges were expected to be laid, a police statement said.
He was on parole when he allegedly used a pump action 12 gauge shotgun to kill four men and seriously injure a woman on Tuesday evening in and around Darwin.
Witnesses and NT Police say the gunman was looking for a man named "Alex" when the shooting began. Police later established Alex, a Darwin resident, was in fact interstate at the time.
Hoffman has undergone surgery in a Darwin hospital for apparent knife wounds "sustained prior" to being Tasered and arrested by police - since late Tuesday night.
He only knew two of the four men he is accused of shooting and killing in a bloody rampage in Darwin this week, according to police.
One of the men he knew is believed to be the 52-year-old Darwin casino security guard Rob Courtney, appears to have tried to defend himself and stabbed the gunman.
He is also believed to have known Mr Sisois, while Mr Baydoun and Mr Hellings are believed to have never met the gunman but were caught up in the rampage while the killer was looking for a person.
Hoffmann was on Thursday formally interviewed by detectives and transferred to the Darwin watch house.
The shooting rampage has raised questions about why Hoffman was released in January after serving a non-parole period of four years of his six-year sentence, given his extensive criminal history.
His latest alleged act of violence, while wearing an electronic monitoring device, took place over the period of an hour in areas around Darwin.
Hoffman had previously breached parole by breaking curfew, for which he was given a 14-day custodial sentence in late April.
When Hoffmann was jailed in 2015, his victim Hussain Garling - who was bashed with a baseball bat in front of his infant son - told the court he "needs to be put away for a very long time, because he will do worse to someone next time".