Ben Roberts-Smith has shown a guilty conscience in colluding with four other witnesses to lie about an alleged murder of an Afghan prisoner he ordered and covered up, a judge has been told.
Barrister Nicholas Owens SC continued his closing address in the Federal Court on Wednesday on behalf of the media companies being sued for defamation.
He said the testimony of several witnesses had been devastated by a deliberate lie inserted into a key mission in Khaz Oruzgan in October 2012, regarding the presence of a partner force soldier dubbed Person 12.
The former SAS corporal is accused of ordering Person 12 to shoot an Afghan prisoner "or I will" through an interpreter.
A serving SAS soldier codenamed Person 14 gave evidence that the Afghan soldier stepped forward and unloaded seven to 10 rounds into the detained man, under those orders.
Mr Roberts-Smith filed pre-trial evidence that Person 12 could not have been present to carry out the alleged execution.
This was backed up by friends and witnesses - Person 27, Person 32, Person 35 and Person 39 - all claiming Person 12 was removed from deployment months earlier after injuring an Australian soldier while shooting a dog.
This story was ultimately "frustrated" by classified defence documents produced at trial, disproving this story, Mr Owens said.
He said it was improbable that five independent witnesses had innocently mistaken the same event, and it was clear collusion in a concerted effort to remove Person 12 from the crime scene.
"Mr Roberts-Smith was either the architect or the knowing beneficiary," he said.
Mr Roberts-Smith is suing The Age, The Sydney Morning Herald and The Canberra Times over 2018 reports claiming he committed war crimes in Afghanistan including murder, and acts of bullying and domestic violence.
The 43-year-old denies all claims of wrongdoing, while the mastheads are defending them as true.
The alleged lie had historical roots, dating back to at least October 2018 when Mr Roberts-Smith called a meeting with Person 14 at a Canberra cafe.
The Victoria Cross recipient asked Person 14 to sign a statutory declaration saying media outlets had wrongly attributed his comments, but Person 14 refused saying that was his recollection.
"Person 14 has stood firm against the pressure that was applied to him by Mr Roberts-Smith," Mr Owens said.
"(It has now) been proved beyond a shadow of doubt, that Person 12 was present, and Person 14 was accurate."
The barrister also pointed to evidence that allegedly shows a post-mission report was doctored, to make the execution look legitimate.
Recorded communications show the prisoner count submitted to Australian headquarters at Tarin Kowt changed 12 minutes before extraction to report a "second engagement".
Another allegation that Mr Roberts-Smith executed a teenage Afghan prisoner in 2012 should be believed due to the level of detail and recall given by another witness, Mr Owens submitted.
The SAS soldier distinctly remembered a "baby face looking young man" with a patchy beard who appeared "shaking like a leaf".
Two days later he asked the decorated soldier what happened.
"And (he said) 'I shot that c*** in the head ...'It was the most beautiful thing I've ever seen'."
Mr Owens said this description matched the forensic evidence of the slain man who Mr Roberts-Smith contends was engaged lawfully.
But Mr Owens accepted the newspapers had lost on one murder allegation after a crucial witness refused to give evidence due to self-incrimination.
Earlier Arthur Moses SC on behalf of Mr Roberts-Smith submitted the media waged a sustained attack on the war hero based on rumour, hearsay and contradictory accounts from jealous and obsessed former colleagues.
Mr Moses said it shattered his reputation and even if vindicated in what was often described as the trial of the century, it would take years for it to fully recover.
The closing addresses are due to continue on Thursday.
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