The SAS is a "toxic environment" where the rumour Ben Roberts-Smith did not deserve his Victoria Cross was commonplace for 12 years, one of his former comrades has told the Federal Court.
The serving SAS soldier codenamed Person 18 on Monday also said a comrade told him several times of witnessing the decorated soldier kick an unarmed Afghan prisoner from a cliff in Darwan in 2012.
Newspapers that Mr Roberts-Smith is suing for defamation have alleged the man was then shot dead by another soldier on his orders.
That soldier would break down in tears every time he retold the story, Person 18 said under cross-examination.
Mr Roberts-Smith is suing The Age, The Sydney Morning Herald and The Canberra Times over reports claiming he committed war crimes and murders in Afghanistan between 2006 and 2012.
The former SAS corporal vehemently denies the allegations, but the publications are relying on truth as a defence.
Person 18 said the culture among the special forces was akin to "a country wives club," where rumours easily spread.
Arthur Moses SC, on behalf of Mr Roberts-Smith, asked what he meant by such an analogy within the SAS.
"(It's a) toxic environment. Any rumour is expanded tenfold."
He explained it was common talk that Mr Roberts-Smith was undeserving of his prestigious VC awarded following the 2010 battle of Tizak in Afghanistan.
During an April 2009 mission to a compound dubbed Whiskey 108 located in Uruzgan province, Person 18 said he heard a radio call that prisoners were located inside a tunnel.
Person 18 recalled words to the effect: "We've pulled someone out of the tunnel".
Mr Roberts-Smith is accused of murdering a man with a prosthetic leg found inside the tunnel and ordering the execution of the other.
The former SAS corporal previously told the court there were no men in the tunnel and denies the allegations as an "outrageous claim".
Person 18 said he and another squadmate who cleared the tunnel of chest rigs, magazines and batteries heard a "burst of ammunition" and the pair looked at each other.
He denied Mr Moses' suggestion that his evidence was false.
On Friday he told the court that he and three others reported concerns about Mr Roberts-Smith to a superior in 2013.
He said the then-regimental sergeant major wasn't receptive to the conversation.
"His response was, it was out of his hands, it was way above his head, and he honestly didn't know what to do with it," Person 18 said.
However, the next year a new regimental sergeant major called the four men back for another meeting, which went for well over an hour as the group covered a list of topics.
Four years later he received a threatening letter in the mail when he again spoke out about alleged war crimes, he told the court.
The letter, received days after he gave evidence to an inquiry probing the allegations, accused him of colluding with other soldiers to tell lies.
"It also stated that I had till the end of the month to change my statement, otherwise I'd go down," he said.
"(It was) signed off, as a friend of the regiment."
Mr Roberts-Smith has denied he wrote the letter, as reported by the newspapers, but the court last month heard from a private investigator - and former friend of the VC recipient - who admitted posting letters to Person 18 on his behalf.
Person 18 is due to return to the witness box on Tuesday.
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