A senior Northern Territory police officer has been questioned about the “militarisation” of the force and its continued use of guns at an inquest into the shooting of an Indigenous teenager.

Kumanjayi Walker, 19, was fatally shot by Constable Zachary Rolfe three times in a bungled arrest attempt in Yuendumu, north-west of Alice Springs, on November 9, 2019.

Constable Rolfe had been sent to apprehend the teen with four other police members as part of a special unit.

Julian McMahon, representing Yuendumu’s Parumpurru committee, also questioned NT Deputy Police Commissioner Murray Smalpage about why the plan “had the whole look of a military operation around the house”.

Mr Smalpage said he could see how the specialist unit could be seen as military-like but he defended the need for NT police to carry arms, citing examples of violence against police in other states.

Earlier, the inquest heard that a series of text messages which may have influenced Constable Rolfe’s defence to a murder charge were not meant for him.

After the shooting, Constable Rolfe received text messages telling him to justify his intent as self-defence against “the s— c— (who) was telling him that he was going to stab the police”.

But Sergeant Ian Nankivell, who wrote the messages, told the inquest he “emphatically denied” that the messages were for Constable Rolfe.

Sergeant Nankivell had sent the messages to a close friend of Constable Rolfe, Constable Mitchell Hansen.

In November, Const Hansen told the inquest that Sergeant Nankivell had sent the messages to him to forward to Constable Rolfe.

The messages outlined an acronym “IAMO plus P” standing for intent, ability, means, opportunity and preclusion, which counsel assisting the coroner Patrick Coleridge said could be seen as a template for justifying Constable Rolfe’s shooting of Mr Walker.

Sergeant Nankivell said the acronym had been part of his police training in Victoria.

“It’s nothing about justification, it’s about mental health,” he said on Thursday.

When asked about his use of the word “critics” in the text messages, he said it referred to self-criticism, not external critics.

“The IAMO plus P is designed just to guide you through the process (of thinking) when your mind is full of fog and dread,” he said.

The messages were never intended to be seen by anyone other than Constable Hansen, he said, despite also acknowledging that he was not close to Constable Hansen nor did they have any relationship outside work.

Constable Rolfe was found not guilty by a Supreme Court jury of Mr Walker’s murder.

The inquest in Alice Springs continues with other members of the NT Police Force, including Assistant Commissioner Bruce Porter, expected to give evidence over the next two weeks.