The Northern Territory Coroner has slammed police for another "botched investigation" into the death of an Indigenous person, but stopped short of accepting that repeated failings are due to institutional racism.

Mother-of-two Kwementyaye Green, 25, died in Tennant Creek in 2013 after bleeding out from a stab wound to her leg which pierced her femoral artery.

She was found dead in a vacant lot in the town, about 500 kilometres north of Alice Springs, with her de facto partner Rodney Shannon lying next to her.

NT Police admitted during the coronial inquest that they destroyed crucial forensic evidence, released Mr Shannon too early, failed to secure the crime scene which potentially allowed Mr Shannon to go back and get rid of evidence, and were "inexplicably preoccupied" with a theory that Ms Green stabbed herself in the thigh.

"During the course of the inquest it became obvious that not only had the investigation taken an inordinate amount of time, but that it was of very poor quality," coroner Greg Cavanagh found.

"The investigation was undertaken by inexperienced officers in an incompetent fashion. In my view, it was so poor that prosecution would only have been possible if the killer confessed."

Police gave "seemingly no consideration" that Mr Shannon might tamper with witnesses or evidence when he was released, noting that it did appear that one crime scene had been "swept and tidied".

"The many failures were not recognised by senior police. How that could be so is worrying. In fact the lack of urgency, intent and competence in the first investigation is mirrored in the actions of senior police," Mr Cavanagh found.

Mr Shannon has never been charged over Ms Green's the death, and the Director of Public Prosecutions has indicated there was not enough evidence to lay any charges against him.

Louise Rankine and Casper Green are hoping the inquest will get to the bottom of what happened to their daughter. ( ABC: Jane Bardon )

'When I'm alone, I think of her'

Louise Rankine travelled to Darwin on Thursday to hear the coroner deliver his findings, but was disappointed to hear that still no-one would be charged over her daughter's suspected homicide.

She said it made her sad, especially for her two grandchildren growing up without a mother.

"It's sad seeing those kids. It's not only my kids, any kids without mother," she said.

"That's why we don't have birthdays for them — we just give them what they want."

While a police officer apologised to her again on Thursday, Ms Rankine said she did not accept it.

"How can you apologise to us again for the third time? He should apologise only once," she said.

"I see them (the police) walking around, and I think to myself, they are walking alive. Where's my daughter? That's what I think.

"We need justice. We need justice. Me and my families and the children, the kids, my grandchildren.

"We don't know what to say, we don't know what to do. We need justice. And it is sad for me. Sometimes I'm with my niece's mob and I sit with them and feel happy with them.

"But when I'm alone, I think of her."

NT coroner Greg Cavanagh was highly critical of the destruction of DNA evidence ( ABC News: Steven Schubert )

Forensic evidence destroyed by police yet again: Coroner

The coroner also expressed his frustration at presiding over yet another case where NT Police destroyed forensic evidence which could have been helpful in securing a conviction.

"Solving cold cases based on DNA is unlikely to happen in the Northern Territory because police continue to destroy forensic exhibits even after they have been asked not to do so. It is outrageous," he said.

He said during the inquest that he didn't want to see another matter in which relevant forensic material had been destroyed.

"The whole concept of cold case investigations must be redundant up here if these kind of exhibits are going to be destroyed, and I continue to find them destroyed.

"I don't understand why there isn't something explicit, in capital letters in the forensic institute or the offices down in the McAulay Centre [police headquarters] that says, 'don't do this'."

He said he was concerned that senior police had failed to manage this even after it had been brought to their attention.

"The community has been denied the potential to bring to justice those that have committed these dreadful crimes," Mr Cavanagh said.

NT Assistant Police Commissioner Michael Murphy apologises to Kwementyaye Green's father Casper. ( ABC News: Stephanie Zillman )

Death not declared major crime for four years

The lead detective of the investigation applied to have Ms Green's death declared a major crime, which would have allocated more resources and more oversight from senior police to the investigation.

That application made it to the desk of then-superintendent James O'Brien, where it seemed to have been lost.

Ms Green's death was not declared a major crime for four years.

But the coroner said this was not the fault of the lead investigator.

"In essence, it appears that not only was a declaration not made, it was not realised it had not been made by senior police until March 2017," Mr Cavanagh found.

"Upon coming to that realisation it still took another eight months to make the declaration."

The coroner also criticised the now Commander O'Brien, who was unable to attend the hearings for medical reasons.

Mr Cavanagh asked Commander O'Brien to make a detailed statement, but noted that statement was only received the day before the inquest recommenced, that it was not detailed, and made no mention of why the major crime application had not advanced.

"This investigation was known to those in the positions exercising governance and supervision to the level of Deputy Commissioner. The question is why nothing was done," he said.

"This is not the first time such issues have arisen."

Mr Cavanagh said there was no supervision and governance from superintendent level to the Commissioner of Police despite many systems designed specifically to provide it.

"Criticising the lower ranks is difficult when the higher ranks were aware of the problems and did nothing," he said.

"What is particularly frustrating is that the higher ranks were spoken to specifically about these problems. Not only did that make no difference, their response to the inquest was late and inadequate."

Mr Green believes police should have better investigated his daughter's death. ( ABC: Jane Bardon )

Institutional racism a 'consideration'

Lawyers for Ms Green's family submitted that the coroner should find the police failings were due to "institutional racism", referring to a report of a failed investigation of a black man in the United Kingdom.

The coroner said that the similarities "certainly invite some consideration", but ultimately could not find so because the UK report was introduced too late in the coronial process to properly put it to senior police.

"I am loathe to make a finding of institutional racism until there is an opportunity to specifically examine that issue throughout an inquest and with all levels of the police force," he said.

"Perhaps, it is lazy policing. Just trying to find the easiest way to wind up an investigation. Or perhaps, it is cultural ignorance."

The coroner made a number of recommendations, including that the Police Commissioner do everything necessary to ensure that specimens and exhibits from coronial investigations are not destroyed without the written consent of a coroner, and to do everything necessary to ensure that specimens and exhibits are not destroyed that relate to sexual offences or other serious offences going to the identity of the alleged offender.

He also recommended that the Police Commissioner ensure that officers investigating major offences "have the appropriate skill, experience and resources", and that senior police undertake their roles in facilitating, supervising and providing governance in relation to all major investigations.

Mr Cavanagh said that he believed that offences may have been committed in connection with Ms Green's death and had reported that to the Police Commissioner and the Director of Public Prosecutions.