Northern Territory police didn't charge a Don Dale Detention Centre guard with assault because he believed he was just "goofing around", an investigator says.
Detective Sergeant Kirsten Engels told the juvenile justice royal commission that former guard Conan Zamolo's maturity level was barely higher than the kids he worked with.
An inmate identified as AT told police he was "clotheslined" by one guard and then chased into his cell by Mr Zamolo, who hit him on the kneecaps with a torch.
Three separate detainees also told police Mr Zamolo recorded one child masturbating in the shower and then posted the footage to social media app Snapchat in 2014.
Former Youth Justice Officer, Conan Zamolo. Source: Royal Commission
Police investigated the claims, including allegations he'd bribed kids to fight each other for junk food, but the bodybuilder was only charged with steroid possession.
Det Sgt Engels told the inquiry she didn't press any charges because she didn't think the boys' evidence was strong enough to win a criminal court case.
She also believed the intent to assault wasn't there based on an unsubstantiated theory that Mr Zamolo thought he was playing a game with the detainee he hit with the torch.
"His maturity level was only one notch above the children he was working with," Det Sgt Engels said.
"It seemed feasible that ... he wanted to be on the same level as those boys, goofing around and joking around with them all the time.
"His behaviour at the detention centre was despicable."
In a police statement, AT said he and three other boys were showering in 2014 when Mr Zamolo filmed them masturbating.
"He thought it was funny cause we were standing on our tippy toes. After that he's told us that he had sent it to everyone on Snapchat," the boy wrote.
Mr Zamolo admitted to wrongfully taking his phone to the shower but said he'd only led the inmates to believe he had filmed them.
Conan Zamolo. Source: Instagram
While giving evidence at the inquiry in March, Mr Zamolo also admitted to jokingly asking detainees to perform oral sex on him, urging a child to eat bird faeces and filming a boy urinating.
The guard was never disciplined for any of those incidents, but was later sacked for an unrelated matter.
It comes as the man who authorised the tear gassing of Don Dale detainees in 2014 says he would do it again and defended the use of the controversial restraint chair.
Former corrections commissioner Ken Middlebrook ordered the gassing of six boys after one escaped his isolation cell and began trashing property in 2014, a scandal which sparked the royal commission.
Mr Middlebrook told Sky News he will return to his role on the NT Parole Board after standing down to give evidence to the inquiry last month.
AAP
