Wrap-up: Week four of the Zachary Rolfe murder trial

The trial, which was expected to finish last week, will now extend into this week with Constable Rolfe's defence lawyer, David Edwardson QC, indicating he still has one card (witness) up his sleeve before counsel make final submissions to the jury.

And remember, if you're not familiar with the background of this case, refer to the week one wrap-up.

The final witness for the prosecution was Detective Senior Sergeant Andrew Barram. The NT Police veteran formerly led the Operational Safety Section of the Northern Territory Police training college, which provides specialist skills training in firearms, defensive tactics and incident management.

Senior Sergeant Barram was quite critical of the actions of Constable Rolfe and his colleagues, who were deployed to Yuendumu to assist with the arrest of the deceased, Kumanjayi Walker.

He was particularly scathing about the way they approached Mr Walker in order to arrest him inside his grandmother's house.

Body-worn camera footage shows officers Rolfe and Eberl walking into the house and approaching Mr Walker, asking him to stand against a wall and questioning him about his identity.

Senior Sergeant Barram said that "completely went against our training", especially as Mr Walker was considered to be a "high-risk" arrest target as he ran at police with an axe three days earlier.

"If you've got someone that you even suspect may be armed, the first thing you're going to want to do is see their hands," he told the court.

"So I don't know why they persisted with going in. They could have done that from the door and said 'Show me your hands', immediately.

"If they suspected that it's Mr Walker, and he's a high-risk offender ... [who] previously has armed himself, why would you put yourself in such close proximity to him?"

Senior Sergeant Barram also told the court he did not believe the second and third shots fired by Rolfe, the ones which are the subject of the murder charge, were necessary

"Things had changed substantially from when the first shot was fired," he said.

"They've changed from being in a standing position, in a fairly equal fight, to Mr Walker being shot in the back, which would affect a person in some way, and being pinned on the ground with his right arm under him."

He said there were other, non-lethal options available to Constable Rolfe at that time such as "empty hand tactics".

However, in cross-examination, Mr Edwardson raised the point in the police training manual that said that when faced with an edged weapon (or scissors as in this case), officers shouldn't use empty hand tactics unless they're unable to use their firearm.

After indicating he was unsure whether or not he would lead evidence in the defence case at all, Mr Edwardson sent a ripple of whispers through the room by announcing that he was calling his client to the stand as his first witness.

Constable Rolfe spoke with confidence during his evidence in chief, often pausing to directly address the jury and explain specific police terms or more complicated aspects of his training to them.

He also spoke briefly about his background - being born and raised in Canberra before spending around five years in the Australian Defence Force, including a stint in Afghanistan.

He said he had found out about "the axe incident" involving Mr Walker the day after it happened, but was concerned that it had been downplayed by the police officers involved.

This, he said, prompted him to show the body worn-camera footage of the incident to a number of his colleagues and alert his superiors - including the Officer-In-Charge of the Immediate Response Team.

After being deployed with the rest of the team to Yuendumu a few days later, Constable Rolfe said he confirmed a number of times with his superiors that his "mission" was to arrest Mr Walker.

On Thursday, Constable Rolfe began detailing the events of the actual shooting, including the revelation Mr Walker reached for his police-issued gun soon after the officers moved in for the arrest.

He said he spotted the "metal blade", which turned out to be a pair of scissors, protruding from Mr Walker's hand, prompting him to "immediately fear for his life".

After being stabbed in the shoulder and firing the first shot, Constable Rolfe said he began fearing for Sergeant Eberl's life as he and Mr Walker were struggling on the floor.

"I could see Kumanjayi's right arm was still moving and stabbing Eberl on the ground," Constable Rolfe said.

"I believed I hadn't incapacitated him at all [with the first shot]."

He explained that everything he did throughout the incident complied with his police training.

One of the central issues in the cross-examination by Crown prosecutor Philip Strickland SC was around Contable Rolfe's allegation Mr Walker reached for his gun during the scuffle before his death.

Mr Strickland accused Constable Rolfe of making the accusation up, given he did not tell any of his colleagues about it after the shooting despite it being "one of the most serious things that can happen to a police officer in a combat situation".

Constable Rolfe said this was because he considered it to be "the least serious thing that happened" during the shooting incident.

He also denied lying when he said he had seen Sergeant Eberl being stabbed by Mr Walker while the pair were struggling on a mattress, and when Constable Rolfe fired the second and third shots.

The cross-examination took an entire court day, and became tense at times, with Constable Rolfe becoming visibly frustrated by some of Mr Strickland's questions.

Towards the end of his questioning, Mr Strickland asked why Constable Rolfe was heard in body worn footage to repeatedly tell Sergeant Eberl "it's all good" after the third shot had been fired.

The court previously heard that Sergeant Eberl hadn't immediately realised that Mr Walker had been shot, and Constable Rolfe said he was explaining to his partner what had happened.

However, Mr Strickland accused Constable Rolfe of justifying his actions after realising he had been too "gung ho".

"How was the situation all good?" he asked.

Constable Rolfe replied that "a violent offender had just been trying to murder two police officers, and he no longer was".

Mr Edwardson asked his client a small number of questions in re-examination before Constable Rolfe left the stand and resumed his place in the body of the court.