The NT Police Commissioner and the Crown prosecutor in the Zach Rolfe murder trial need to explain to the public why it appears they misled the Supreme Court by using evidence that was manipulated by investigators and relied on a witness that had earlier been found to be “pressured” to participate, a national legal expert says.

The shock revelations came from a draft coronial report prepared by the NT Police that Jamie Chalker had attempted to bury from the public and the defence team, but reported on this week by the NT Independent.

The report, prepared in part by highly-respected Superintendent Scott Pollock before he was removed from the case, found that police investigators forced witnesses to provide statements with threats of disciplinary action if they didn’t participate, found the crown’s use-of-force witness was biased and didn’t understand the law, and also found that a supposedly independent report prepared by an American use-of-force “expert” had been “edited” at the request of investigators.

The NT Police executive and the Crown prosecutor were aware of the contents of the report before the murder trial commenced, the NT Independent understands.

Constable Rolfe was charged with murder in the 2019 shooting death of Yuendumu man Kumanjayi Walker but was found not guilty by a jury following the five-week trial in March.

The Rule of Law Institute of Australia’s vice president Chris Merritt said the findings of the draft police report “suggests some of the evidence presented at Constable Rolfe’s trial may have been manipulated to favour the prosecution case”.

“If the matters outlined in the draft report are accurate, they suggest unknown parties associated with the investigation may have attempted to tilt the scales of justice and mislead the Supreme Court.

“If this is what happened, it is a tribute to the court that it overcame these impediments and acquitted Constable Rolfe.

“However the matters outlined in the draft report need to be properly examined and, if they are accurate, those responsible need to be called to account.”

Mr Chalker was sent questions for this story yesterday afternoon but did not respond.

Crown prosecutor Philip Strickland was also contacted for comment but declined to respond. Current Director of Public Prosecutions Lloyd Babb also declined to comment for this story.

What the secret report found about police criminal investigation and unreliable witnesses

The draft coronial report found that Sergeant Andrew Barram – who had testified against Constable Rolfe at the trial – had based his statement to investigators on incorrect information, was “pressured” to be involved in the investigation and that he was also subject to “confirmation bias”, but that his findings were blindly accepted by the investigative team.

“There was no challenge or peer review by investigators conducted on the statement of Barram. It was accepted as reliable without being subject to any scrutiny by investigators,” the report stated.

It also found Sgt Barram was pressured to testify by unknown parties in the police, which “potentially compromised his integrity”.

“The pressure brought to bear on him to provide his ‘expert’ opinion was done so in haste and, similar to [American use-of-force expert] Professor [Geoffrey] Alpert, prior to all available and relevant evidence, including possible exculpatory evidence, being made available to him for consideration,” the report found.

Prof Alpert had been hired by the NT Police at a cost of nearly $100,000 to provide an independent assessment of the shooting death, who agreed with Sgt Barram that shots two and three fired by Constable Rolfe were excessive.

However, the internal police report shows Prof Alpert did not have all of the facts of the case given to him and that his independent report was being “corrected” by investigators.

“He was also not provided with all materials of relevance in reaching his opinion that Rolfe’s use of force was exactly the same as what Barram had concluded, as not ‘reasonable, necessary, proportionate and appropriate to the circumstances’,” the report stated.

“Professor Alpert provided his statement well before statements from other medical experts became available. In doing so he did not have the opportunity to properly consider all evidence potentially relevant to his own area of expertise.”

The coronial report also found that Prof Alpert’s findings were being manipulated by investigators.

“The email correspondence between investigators and Professor Alpert suggested that the investigation team were editing (correcting) the draft statement of Alpert,” the report stated.

Mr Merritt said the troubling findings indicated that “unknown parties edited or changed a draft statement by an expert witness”.

“That witness was not provided with information that favoured Constable Rolfe,” he said.

Prof Alpert’s report was used at the committal hearing to find Constable Rolfe fit to stand trial for murder in the Supreme Court. Prof Alpert was not used at the murder trial, but Sgt Barram testified as the Crown’s star use-of-force witness despite the police executive having seen the concerns about his evidence in the internal draft coronial report.

The report also found that NT Police investigators were blurring the lines between a coronial investigation and a murder investigation and not following the “usual rules of evidence relating to the collection of witness evidence for a criminal investigation…”.

Some witnesses appearing before investigators were threatened with disciplinary action if they did not provide statements, which is typically done for a coronial investigation, not a criminal matter.

“It is unknown why the criminal investigation team elected to refer to or attempt to use powers contained within the Coroners Act 1993 [NT] when gathering their witness evidence,” the report concluded.

“In the case of a criminal investigation there is no rule of law that compels a police witness to answer questions or to provide a statement. During a coronial investigation or at inquest however this may not be the case.”

Mr Merritt said that was also concerning for the perception of a fair trial and investigation.

“Other witnesses, according to the draft report, gave evidence at the murder trial after being subjected to threats and pressure,” he said.

“The material in the draft report needs to be substantiated. If true, it raises serious concerns about whether unknown parties tried to prevent Zachary Rolfe receiving a fair trial.”

Chalker tries to get the NT Independent held in contempt of court for publishing this story

This morning, about 16 hours after Mr Chalker received the questions for this story, a taxpayer-funded lawyer representing the NT Police’s interests at the coronial inquest incorrectly accused the NT Independent of breaching a non-publication order and demanded the Coroner hold this publication in contempt of court for its reporting.

The extraordinary request was made to Coroner Elisabeth Armitage, however she said she would reserve her decision on a ruling.

The six-part investigative series revealed a number of police failures in the lead up to the shooting death of Kumanjayi Walker, which was sourced from the draft coronial investigation report prepared in part by Supt Pollock and Commander David Proctor, who controversially replaced him at the request of the police executive management team before Supt Pollock could finish.

The Coroner’s inquest is currently reviewing the events that led to the shooting death of Mr Walker. It is not expected to investigate the matters of a potentially corrupted murder investigation detailed in the internal police report.

The report the NT Independent has obtained is not listed on the annexure of material currently under a non-publication ban.