Steven Freeman, 24, was bashed unconscious and needed urgent surgery after he was attacked in the Alexander Maconochie Centre several hours after he was remanded in custody in late April.

He was placed in an induced coma for a week and there were concerns he could have been left with a permanent brain injury.

The circumstances surrounding Freeman's near-fatal bashing raised serious questions and sparked calls from the Indigenous community for an independent inquiry, which the ACT government resisted.

Freeman, who was an unsentenced detainee, had been placed with sentenced prisoners and a CCTV camera that covered the entrance to his cell was turned away at the time of the attack.

Police launched an investigation into the bashing and revealed in October that forensic testing of a bloodied shoe and fingerless gloves had helped them identify three suspects.

It is understood Freeman had no memory of the attack.

But police said on Wednesday that the investigation had been finalised with the help of ACT Corrective Services and no charges would be laid.

In October, Fairfax Media revealed that Freeman's legal team at Sharman Lynch Solicitors had put the ACT government on notice that a personal injury claim would be launched and proceedings were in their early stages.

Winnunga Nimmityjah Aboriginal Health Service previously said the case still raised problems of "major concern".

Chief executive Julie Tongs criticised the level of information released to the community and said it would be "sad indeed" if silence was being used to protect the government from legal consequences.

Ms Tongs said the case was further fuelling mistrust between the Indigenous community and the justice and corrections systems.

ACT Policing said anyone with information about the incident could still contact Crime Stoppers on 1800 333 000.