Constable Rolfe, 30, faced the seventh day of his month-long murder trial on Tuesday, with the court hearing evidence from his colleague and another officer in Yuendumu on the night of the shooting, Constable James Kirstenfeldt.

Constable Kirstenfeldt, who is a former soldier like Constable Rolfe, was a member of the Immediate Response Team (IRT) sent from Alice Springs to Yuendumu to help arrest Mr Walker on the night he died.

Constable Rolfe was also a member of that team.

Constable Kirstenfeldt said he had been informed by the local Officer in Charge, Sergeant Julie Frost, that there were no nurses in the community as they had been advised to leave that day following a spate of break-ins to their homes.

He said he believed Mr Walker was the ring-leader.

"Walker ran a group of 'breakers' I think she [Sgt Frost] referred to, of young fellows that look up to him and follow him, and they break into all their [the nurses] houses," Constable Kirstenfeldt said.

Because the nurses had left the community, medical professionals were required to travel in from Yuelamu, a community around 45 minutes away, in the case of an emergency.

Constable Rolfe shot Mr Walker three times in the chest just after 7.20pm when Mr Walker stabbed him in the shoulder with a pair of scissors in an attempt to evade arrest.

Despite the first aid efforts of police officers, Mr Walker was declared dead at 8.36pm when Yuelamu health staff arrived.

Constable Rolfe has pleaded not guilty to Mr Walker's murder in relation to the shooting as well as two lesser alternative charges

Crown prosecutor Philip Strickland SC asked Constable Kirstenfeldt if he and other officers had "a bit of a laugh" about the fact that there were no nurses.

"Uh, no," Constable Kirstenfeldt replied.

"You didn't?

"No."

The day's court sitting got off to a rocky start, with presiding Justice John Burns closing the court almost as soon as it opened for the day, citing an issue with the jury.

Around 90 minutes later, Justice Burns reopened the court and announced a juror had been dismissed.

"I have discharged a juror from the jury and the trial will proceed with the remaining jurors," he said.

"Both the accused and the Crown have accepted the assurances given by the remaining members of the jury that they can assess the issues on an unbiased basis."

It is unclear why the juror was dismissed.

A ballot was conducted to select a reserve juror to join the jury proper.

The court also heard from the Senior Aboriginal Community Police Officer in Yuendumu at the time of the shooting, Derek Williams.

Mr Williams, who was a family member of Mr Walker's, described him as a "quiet, shy young fella."

He said Mr Walker's biological mum sniffed petrol when she was pregnant with him and agreed with Mr Strickland's description of Mr Walker as "a bit slow."

Mr Walker was an orphan at the time of his death, being raised by adoptive parents.

He also agreed he was "surprised" by an incident on November 6 when Mr Walker violently threatened two other police officers with an axe.

They had cornered him in a home at the community and were attempting to arrest him for fleeing an alcohol rehabilitation clinic about a week earlier.

The trial continues on Wednesday.

With AAP