Antoinette Carroll is the co-ordinator of the Youth Justice Advocacy Project at the Central Australian Aboriginal Legal Aid Service and worked with Dylan Voller for seven years.
Voller has a long criminal history.
The 19-year-old has been in and out of youth detention since he was 11 years old.
But Ms Carroll has told the Royal Commission Voller is not naturally a violent person.
"He's not been exposed to that at home in his home life. His sisters are very nurturing, his older brother's a pure, positive role model for him as well. I've worked with young people who are violent, and have violence offences, but my experience with him was very empathic. So, it was very sad that he gone down the road."
She says authorities were disorganised in how they dealt with Voller.
"What became very evident was that obviously, Dylan was a young person who presenting with challenging behaviour. There was overwhelming lack of therapeutic supports in place. But, importantly, there was a lack of co-ordination in relation to how he should travel through the criminal justice system."
Ms Carroll says the decision to incarcerate Voller was the wrong one.
"In my view, and I think many people's view, (he) was still at the very low end of offending. And then he was sentenced to eighteen months (in jail), which really was quite devastating for such a young child to receive that... such a long, punitive sentence."
She says education would, and should, have been a key preventative measure for Voller.
Voller has spoken of his troubles getting education in front of the Royal Commission.
He finished his formal schooling at the age of ten.
Ms Carroll has told the Royal Commission not enough was done to get Voller a proper education.
"I'm of the view that no stone should have been left unturned to get him into a classroom environment with the appropriate supports in place, like one-on-one (tutoring), or (a) counsellor on hand, or whoever needs to be there. But, again, there just seemed to be endless barriers to getting him into mainstream edcuation. And it's pretty evident he's a highly intelligent young man."
Ms Carroll has used the example of Voller to show what she believes is the ill-equipped nature of the Northern Territory's justice system to cope with young offenders.
It's not just the prison system that's been highlighted - Ms Carroll has also taken aim at the courts.
"Because it's so ad-hoc and so chaotic, young people come into that space completely frazzled, essentially. And it's busy, there's not a whole lot of time to take instruction, there's a lack of therapeutic supports within the court space, no appropriately-trained practitioners across the board."
Ms Carroll says Voller was put on the "merry go round" cycle of re-offending.
She says the lack of help for young people when they get out of jail is often their ticket to going back inside again.
"Sadly, it's really unclear for many young people, coming through the system, when they're released, what's next. Where to from here, essentially. Essentially, they gravitate back to their peer group support, and back (into) the criminal justice system."
Ms Carroll has questioned the need for youth detention centres, such as the one Voller was housed in when he was tear-gassed and shackled.
She says there should be early intervention and diversionary programs in the Northern Territory as an urgent priority.
The Royal Commission continues.
