An expert has revealed why Ben Roberts-Smith may not have been placed in handcuffs after he was arrested on a plane and led across the tarmac into a cop car.   

The 47-year-old was taken into custody by Australian Federal Police on Tuesday over allegations he killed unarmed civilians while deployed in Afghanistan between 2009 and 2012. 

He is also accused of failing to stop members of his unit from killing three others. 

But photos of the arrest have sparked questions about why officers chose not to use handcuffs after he arrived on a Qantas flight from Brisbane to Sydney.

Criminal psychologist Tim Watson-Munro told the Daily Mail several factors would have contributed to how authorities planned to approach the veteran.

'I'm sure they made a fairly calculated decision that he was not a risk of flight, he was not going to cause a ruckus, and that he would, in all likelihood, leave the airplane and the airport peacefully,' he said.

'Who knows, he may have asked that he not be cuffed. 

'It may have been, notwithstanding the grave nature of the allegations, which have yet to be proven in a court of law, a mark of respect, given that he still holds a Victoria Cross.'

Mr Watson-Munro said that Roberts-Smith may have 'obvious physical prowess' and have been surprised by the arrest, but wasn't likely to have 'done a runner'.

'He had his two twin daughters with him, as I understand it. They observed all of this, and I would imagine that he was endeavouring to maintain his dignity,' he said.

'Generally, police handcuff people for two reasons: primarily to restrain - so you've got a heavy criminal, inevitably they will be handcuffed.'

The second reason, he said, was to prevent a suspect from escaping or entering into a physical confrontation with officers. 

Footage of the arrest showed Roberts-Smith wearing a polo shirt, jeans and a cap as he was led off the aircraft and escorted across the tarmac to a white four-wheel drive.

A Nine News television camera crew had been waiting at the airport to film the 47-year-old's arrest when the plane touched down.

'So when officers arrived, I'm sure that he was quite surprised, if not shocked by their appearance,' Mr Watson-Munro said.

'But of course, he's a highly trained SAS soldier, so compared to what he has witnessed in warfare, I think the arrival of a couple of AFP members at Sydney Airport would not necessarily ruffle him.

'He seemed reasonably calm - part of his training, I think.'

Roberts-Smith, who has always maintained his innocence, will remain in custody for two months.

During a mention in Bail Court on Wednesday, criminal lawyer Jordan Portokalli said that there was no application for bail.

The matter has been scheduled for a brief status hearing on June 4, when the SAS soldier will appear via audio-visual link from prison. 

Roberts-Smith sued Nine newspapers and journalists Nick McKenzie and Chris Masters for defamation over their reports in 2018, which accused him of war crimes.

In 2023, Justice Anthony Besanko found the claims that Roberts-Smith was responsible for the murder of four unarmed male civilians while deployed in Afghanistan were substantially true.

He had appealed his 2023 Federal Court loss, disputing Justice Besanko's findings, arguing they were not backed up by sufficient evidence for such serious claims.

Last year, Australia's highest court refused the former soldier's application to appeal the Federal Court findings.

The Age's McKenzie and Masters were first to report details of Roberts-Smith's arrest on Tuesday morning. 

It was the result of a joint investigation between the AFP and the OSI, which began in 2021.

In total, authorities commenced 53 investigations involving allegations of war crimes by Australian Defence Force members in Afghanistan. 

Officials have said 39 of them are not being actively pursued, subject to further evidence emerging.

Ten investigations into allegations of criminal offences under Australian law related to breaches of the Laws of Armed Conflict by ADF personnel are ongoing.

One investigation resulted in another former SAS soldier being charged with murder. 

That case has been listed for trial in February next year in the NSW Supreme Court.