Former constable Zachary Rolfe arrested a child hiding in a bin by pushing it over and dragging him from it, a year before killing Indigenous teenager Kumanjayi Walker.
Mr Rolfe shot Mr Walker, 19, three times while on duty in the remote community of Yuendumu in November 2019 and was acquitted of murder in a five-week trial.
Mr Rolfe took the stand at an inquest into Mr Walker's death on Monday and was asked questions about a use-of-force incident in 2018.
The court was shown body-worn footage of the incident where Mr Rolfe was shown arresting a 14-year-old boy in Alice Springs.
The boy was hidden in a bin and Mr Rolfe then closed and leant on the lid of the bin.
He then forcefully pushed the bin over and dragged the boy from the bin before putting him in handcuffs.
Once arrested the boy can be heard saying "Sorry sir, sorry sir, sorry for running sir".
Mr Rolfe said he had not been trained on how to arrest someone in a bin.
The court has earlier heard about other use-of-force incidents which he is yet to be questioned over.
He also faced questions about his falsified police applications.
The former soldier was convicted of theft in the internal military court for stealing tobacco from a colleague in 2012 during a drunken night out with colleagues.
In 2011 he was also fined $300 for public nuisance with violent behaviour for his involvement in a Townsville brawl.
In 2016 he applied to join police forces in the NT, Queensland and Western Australia.
But he checked "no" on questions asking whether he had any previous altercations with police or was ever charged or convicted of any offences.
In March 2016, the Queensland Police integrity unit banned Mr Rolfe from re-applying for ten years because he had not disclosed the fine.
Mr Rolfe said it was an innocent mistake.
"I suggest to you that you deliberately didn't disclose that you had spoken to police about that incident," Counsel Assisting the coroner Peggy Dwyer said.
"No that's not correct... I didn't remember," he answered.
A week later, the then 24-year-old was interviewed by NT Police, his last preference for police placement, and divulged the 2011 Townsville incident.
"I told him about the event ... and I believe he laughed and said 'you'll fit in here'," Mr Rolfe said.
He also admitted he lied on the police drug checks by checking "no" to prior drug use when he had used marijuana as a teenager and MDMA as an adult, saying it would give him the best chance of getting into the force.
The former NT Police constable was also asked about racist culture within NT Police, saying other officers had lied earlier in the inquest when they said racism was not pervasive in the force.
Mr Rolfe said racism was unacceptable but accepted in NT Police, used nearly daily and normalised.
He said the NT Police Territory Response Group, issued an annual award to its officers, using a derogatory name for Indigenous people, which is now under investigation after Mr Rolfe's evidence.
Mr Rolfe reflected on racist text messages he sent, shown at the inquest in 2022, saying language he used to describe Indigenous people would have caused hurt to several people.
"That killed me, I'm sorry for that," he said.
Mr Rolfe's legal team has argued questions regarding eight use-of-force incidents, his police force application and some of the racist text messages should not be admissable.
The inquest resumed on Thursday, with the constable's former manager Sergeant Lee Bauwens telling the coroner Mr Rolfe's fatal shooting of the teenager was "appropriate policing".
Mr Rolfe has lost several challenges to avoid answering questions at the inquest, including asking the NT coroner to step aside due to perceived bias.
His evidence is set to take all week.
