Solicitor Michael Bartlett criticised the probe into Charli Powell's death, telling the NSW Coroner's Court on Thursday that Queanbeyan police rushed into declaring it a suicide.

"[That decision] was precipitous and not justified at the time, and they stuck to that story because of the errors in the investigation," Mr Bartlett told the court.

His comments came on a day NSW deputy state coroner Harriet Grahame had been due to deliver her findings on the February 2019 death of Charli, who died at Freebody Oval.

Ms Grahame decided to delay her findings, however, in order to allow the NSW Police commissioner's lawyers to provide the court with evidence relevant to a particular decision Leading Senior Constable Emma Tubman made in the early stages of the investigation.

The nature of that decision cannot be detailed for legal reasons.

Ms Grahame noted she had, since four days of evidence at inquest hearings in March, received written submissions from Mr Bartlett, who acts for Charli's mother Sharon Moore, and counsel assisting the coroner Jake Harris.

She said she understood Mr Bartlett's submissions to suggest deficiencies in the police probe should contribute to her making an open finding about the manner of Charli's death.

Mr Bartlett has previously challenged Charli's former boyfriend, Rohan Allan Rosewarne, about whether the convicted criminal had killed her and then staged a suicide scene.

Rosewarne, who is serving a 10-year jail sentence in the ACT for crimes unrelated to Charli's death, angrily denied this in March and screamed at Mr Bartlett over an audio-visual link on a dramatic day that left Ms Grahame admitting she felt "rattled".

Mr Harris suggested a different conclusion in his closing submissions, telling the court Charli's manner of death was "self-inflicted ... in the context of domestic violence".

He said there was evidence Rosewarne had been physically and verbally abusive towards Charli, and that this violence was likely to have contributed to the Indigenous girl's state of mind at the time of her death.

Mr Harris noted evidence that included Rosewarne having saved Charli's number in his phone under the name "Slut", and threatening text messages that included a warning that he would "stab ya in ya throat".

In her last message to Rosewarne, Charli threatened to leave him and tell every girl he was with that he was "a woman basher and a liar and a cheater and most of all a user".

Ms Grahame is now planning to deliver her findings on October 7.

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