A key defence witness who allegedly killed an Afghan man during a 2012 mission after receiving orders from Ben Roberts-Smith is attempting to avoid testifying at the veteran's defamation trial.
The witness, codenamed Person 66, was subpoenaed by publisher Nine Entertainment, which is being sued by Mr Roberts-Smith over newspaper articles published in 2018.
The war veteran claims he was defamed by false allegations in those stories of unlawful killings, bullying and domestic violence.
Person 66 had not killed anyone prior to a mission in Syahchow during one of his deployments to Afghanistan in October 2012, according to Nine's court documents.
Mr Roberts-Smith allegedly directed Person 66 to shoot an Afghan man who was, at the time, a PUC (person under control), and he allegedly "did so".
After the incident, Mr Roberts-Smith allegedly said he had "blooded" Person 66, a phrase referring to junior operators getting their first kill in action.
Person 66 initially objected to answering a question about the number of missions he took part in when Mr Roberts-Smith was a patrol commander, citing potential self-incrimination.
His position remained unchanged despite being offered a certificate under the Evidence Act which would mean his evidence could not be used against him in an Australian court.
Nine's barrister, Nicholas Owens SC, sought to have the witness directed to give evidence, triggering a lengthy legal debate.
Barrister Jack Tracey, representing Person 66, said the expected evidence was "of a nature that if it were given, would involve self-incrimination of the gravest kind".
Mr Tracey argued there was a "heightened risk" of future charges due to investigations by Australian Federal Police and the Office of the Special Investigator.
"If that occurred ... his forensic disadvantage would be very substantial and that's notwithstanding the existence of a certificate," Mr Tracey said.
The barrister also cited his client's post-traumatic stress disorder and said the effect of him giving evidence would "put his wellbeing and indeed his life at risk".
The court heard there was no other eyewitness testimony concerning the alleged incident at Syahchow.
Mr Owens argued Person 66's evidence was "highly relevant", including towards establishing the substantial truth of two central imputations in the case.
Proving the Syahchow incident represented "an independent path home to victory", Mr Owens said.
Last year, Mr Roberts-Smith was asked in the witness box whether he ordered Person 66 to kill a prisoner and he replied: "I did not."
The veteran told the court during the mission, insurgents were shot in an "agriculture area" outside some compounds, but he could not recall who initiated the engagement.
He said he threw a grenade because there was no return fire or yelling and they needed to ascertain if the insurgents were dead.
Two dead insurgents were found in vegetation, Mr Roberts-Smith said.
The veteran said he didn't know whether any PUCs were taken.
Former elite soldier and Assistant Defence Minister Andrew Hastie, who was also on the mission, previously told the court it was his view "Person 66 was blooded".
He recalled seeing "12 to 15" PUCs up against a wall being tactically questioned and Person 66 "looking nervous".
"I just thought that's not the person I know, happy-go-lucky sort of country Aussie," he said.
Mr Hastie said he went to another area and heard a radio call that shots had been fired, but did not hear any.
He said Mr Roberts-Smith later walked past him and said: "Just a couple more dead c***s."
Justice Anthony Besanko will make a decision about Person 66's evidence tomorrow afternoon.
