By Miklos Bolza in Sydney

The suggestion two insurgents killed during a raid involving Ben Roberts-Smith were unarmed prisoners was speculation and in contradiction with an official military document, an appeals court has heard.

The disgraced war veteran sat with his parents in court on Monday as his team of top-tier barristers attempted to overturn his landmark defamation loss over war crimes media reporting.

Representing the 45-year-old ex-SAS corporal, Bret Walker SC said findings that Mr Roberts-Smith was involved in the unlawful killing of two unarmed prisoners at a compound called Whiskey 108 was based on testimony contradicted by an official patrol debrief.

The document mentioned the deaths of nine enemies killed in action including two “squirters” – military speak for insurgents attempting to flee a battlefield – and did not refer to any prisoners being captured on the day of the April 2009 event.

In June, Federal Court judge Anthony Besanko found Mr Roberts-Smith was involved in four unlawful murders, including two at Whiskey 108 involving insurgents who emerged from a secret tunnel located in the compound.

Mr Walker told the Full Court there was no explanation as to why the judge had preferred witness testimony based on memories of events 13 years ago over documents created closer in time to the event.

Nowhere had Justice Besanko explained how he found the patrol debrief had been “nefariously corrupted” to cover up the murders, Mr Roberts-Smith’s barrister told three appeal judges and a packed courtroom.

A judge could not infer a document had been part of a cover-up if it contradicted witness testimony given to a court, he said.

“That would be absurd and unfair and purely speculative.”

A second military document, the details of which were confidential, also supported the version of events described in the patrol debrief, the barrister added.

Differences in testimony between those on the ground, including whether only one person or two emerged from the tunnel, were not adequately explained by the judge and were “shrugged aside”, the court heard.

“Nothing is supplied so as to distinguish in any way at all between the reliability of different versions by different people all supposedly in the same place,” Mr Walker said.

The barrister argued that Justice Besanko erred by failing to give enough weight to Mr Roberts-Smith’s presumption of innocence when delivering his judgment.

The 10-day appeal challenges further findings from June, including that the decorated soldier kicked a handcuffed prisoner off a cliff and ordered him executed.

He is also challenging a finding that he machine-gunned a man in the back and took his prosthetic leg back to Australia to use as a beer-drinking vessel.

In his decision, Justice Besanko found Mr Roberts-Smith bullied fellow soldiers to prevent them speaking out about his actions, threatened witnesses and hired private investigators to track them.

The 2600-paragraph judgment was a comprehensive loss for the Victoria Cross recipient in his defamation case over 2018 reports in Nine-owned papers The Age and The Sydney Morning Herald, plus The Canberra Times.

If the legal challenge is unsuccessful, Mr Roberts-Smith and his financiers at the Seven Network – including billionaire Kerry Stokes – will be on the hook for tens of millions of dollars in legal costs.

In November 2020, a report into alleged war crimes by special forces in Afghanistan found credible evidence 39 civilians and prisoners were unlawfully killed by Australian troops, while two others were subject to cruelty.

Two years later, more than 40 alleged offences were under investigation.

Mr Roberts-Smith has not been charged.