The Aboriginal teenager died after Rolfe, 30, shot him three times during a failed arrest in Yuendumu, 290km northwest of Alice Springs on November 9, 2019.

Prosecutors say Rolfe went "too far" when he fired the second and third shots, which are the subject of his murder charge, because Mr Walker, 19, was "effectively restrained" by another officer.

Rolfe says he was defending himself from a violent offender who had stabbed him with scissors held in his right hand.

Expert witness Keith Towsey on Friday said Rolfe's first shot into Mr Walker's back was unlikely to have prevented him using his right arm.

"It has not struck any major organs to cause a major haemorrhage," he told the Northern Territory Supreme Court in Darwin.

"It has not affected the major muscle groups that provide power to the shoulder and it has not affected any of the nerve supply of the shoulder.

"Anatomically, I cannot see how the missile tract at A1 would affect his ability to use his right arm."

Dr Towsey said Rolfe's second shot into Mr Walker's left torso likely killed him.

"It has gone from one side of the body to the other and in doing so it has passed through several major organs, in particular the liver, the kidney and spleen," he said.

"These three organs, in particular, have a very rich blood supply and penetrating trauma to them causes quite extensive bleeding."

Dr Towsey also said a pair of scissors could be used to inflict a fatal injury if they penetrated a person's arteries or veins.

But he rejected an assertion by Rolfe's lawyer, David Edwardson QC, that the scissors Mr Walker used to stab the constable were surgical scissors.

"They just look to me like a generic pair of scissors that you get at any stationery shop," he said.

Earlier, the jury heard that Senior Constable Anthony Hawkings, who witnessed Rolfe fire the second and third shots, had previously told investigators Mr Walker was contained when he was fatally shot.

Prosecutor Philip Strickland SC reminded him of his statement to police soon after the incident in which Sen Const Hawkings Rolfe and Constable Adam Eberl "looked like had contained (Mr Walker) or were containing the guy".

But on Friday he said Rolfe and Const Eberl "were in the process of attempting to contain Mr Walker" when the shots were fired.

"It was a very active situation.

"I saw them wrestling on the ground."

Sen Const Hawkings also agreed with Mr Edwardson that Mr Walker had not released the scissors he stabbed Rolfe in the shoulder with when he was shot.

"He was not incapacitated was he?" Mr Edwardson said.

"No," Sen Const Hawkings replied.

Sen Const Hawkings' body-worn camera recorded him running towards an open door at Mr Walker's grandmother's house after Rolfe fired his first shot.

As he approached the doorway Rolfe can be seen standing over Const Eberl and Mr Walker just before he fires the second and third shots.

Sen Const Hawkings told the court on Thursday that Mr Walker was laying on a mattress on the ground when Rolfe fired.

Moments later the camera records Mr Walker laying face down with his arms and hands behind his back as Rolfe and Const Eberl handcuff him.

He was still holding the scissors in his right hand.

Prosecutors have conceded the first shot, which was fired while Mr Walker was standing and resisting arrest, was justified.

Rolfe's second and third shots were fired from a distance of about 5cm.

The court also heard that Sen Const Hawkings' police notebook, which he used to record details about the day Mr Walker died, went missing while detectives were investigating the shooting.

He said he did know how he lost it.

The trial continues on Monday.

Australian Associated Press