Constable Rolfe, 30, faced a gruelling and at times tense cross-examination at the hands of Crown prosecutor Philip Strickland SC on Friday, as the fourth week of his murder trial came to a close.

He has pleaded not guilty to murder, as well as two alternative lesser offences, for shooting Mr Walker, 19, three times in the chest during an attempted arrest in the central Australian community of Yuendumu in November 2019.

Constable Rolfe told the court during his evidence-in-chief on Thursday that Mr Walker had his hand on his police-issued Glock at one point during the altercation, which turned fatal.

But on Friday, Mr Strickland asked him why he didn't tell any of his colleagues this had occurred.

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"You never said to Mr Eberl [Constable Rolfe's police partner at the time], never in this entire incident that he had his hand on your Glock?" he asked.

Constable Rolfe replied, "Correct, I didn't."

Mr Strickland said, "[But], it's one of the most serious things that can happen to a police officer in a combat situation."

Constable Rolfe replied, "I think in this incident, it was the least serious thing that happened."

Constable Rolfe agreed he didn't tell any of his other colleagues, including other members of the Immediate Response Team or the Yuendumu Officer-In-Charge Sergeant Julie Frost, about the incident.

"If it was the case that Kumanjayi Walker had tried to grab your gun, that would be one of the first things you would say wouldn't it?" Mr Strickland asked.

"You have just made up the fact that Walker had his hand on your Glock didn't you?

Constable Rolfe replied that was "incorrect".

Constable Rolfe also denied lying when he said he had seen Mr Walker stabbing Remote Sergeant Eberl after he had wrestled Mr Walker to the ground, and before Constable Rolfe fired the second and third shots - which are the subject of the criminal charges.

The court has previously heard Mr Walker produced a pair of scissors and stabbed Constable Rolfe in the shoulder when he moved in to arrest him, and was still holding them after the third shot was fired.

Constable Rolfe became visibly frustrated at points in the cross-examination, including while being asked about any planning that took place before arresting Mr Walker.

He said he did not discuss any such plan with his fellow officers because he trusted his and their training.

Mr Strickland asked if Constable Rolfe should have applied "if-then thinking" - a term the court has previously heard is used in police training around planning for potentially risky situations.

"'If-then thinking' isn't confined to what's inside your head, is it?" Mr Strickland asked.

Constable Rolfe quipped, "By definition it probably is. It's called thinking."

Mr Strickland questioned why Constable Rolfe was heard to repeat the phrase "it's all good" to Sergeant Eberl immediately after the final shot was fired.

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

In a response that elicited a ripple of emotion among Mr Walker's supporters in the courtroom, Constable Rolfe replied that "a violent offender had just been trying to murder two police officers, and he no longer was".

The trial, which was due to finish on Friday, is set to extend into next week, with the jury not sitting on Monday for a personal reason of one of the jurors.

Constable Rolfe's lawyer, David Edwardson QC, told the court he intends to call one more witness for the defence before counsel make closing addresses.