Australia’s most decorated living soldier is expected to be charged with five counts of war crime murders after he was arrested at the Sydney airport on Tuesday.

Police identified him as a 47-year-old former Australian Defence Force (ADF) member and the media named him as Ben Roberts-Smith.

Roberts-Smith, a recipient of the prestigious Victoria Cross, was arrested at the domestic terminal after a flight from Brisbane, Australian federal police and the Office of the Special Investigator said.

He will be charged with five counts of war crimes in connection to the murder of five people in Afghanistan between 2009 and 2012, ​Australian Federal Police (AFP) said. The maximum penalty for each charge is life imprisonment.

In 2018, several Australian newspapers published allegations that Roberts-Smith had committed war crimes in Afghanistan, including murdering civilians and ordering subordinates to carry out executions while serving in Australia’s Special Air Service Regiment (SASR). He sued for defamation, arguing the reports falsely portrayed him as a criminal who disgraced his country and its military, but the outlets defended their journalism as truthful.

The court ultimately sided with the newspapers on the civil standard of the “balance of probabilities”, finding key allegations substantially true.

Among the most serious findings were that in 2012 he kicked a detained Afghan man, Ali Jan, off a cliff and then ordered a subordinate to shoot him dead, and that during a 2009 raid he ordered the execution of an unarmed elderly man and personally killed a disabled detainee. Evidence also emerged of soldiers allegedly treating a prosthetic leg taken from a victim as a trophy.

In September last year, the High Court said it would not hear his appeal against a federal judge’s civil court finding in 2023 that Mr Roberts-Smith likely killed non-combatants unlawfully in 2009 and 2012.

Three federal court judges had unanimously rejected his appeal against that finding in May.

The High Court decision left the war veteran with no more legal options in a defamation case he started in 2018 when newspapers accused him of a range of war crimes.

Roberts-Smith has called the allegations against him in the defamation case as “egregious” and “spiteful”.

Australian Federal Police (AFP) commissioner, Krissy Barrett, said it will be alleged the victims were unarmed Afghan nationals who “were not taking part in hostilities at the time of their alleged murder”.

She said the charges come as a result of a “complex” investigation that was undertaken “thoroughly and meticulously” since 2021 by the AFP and Office of the Special Investigator (OSI), according to the Australian Broadcasting Corporation.

“It will be alleged the victims were shot by the accused or shot by subordinate members of the ADF in the presence of, and acting on the orders of the accused,” she said. On Tuesday, prime minister Anthony Albanese refused to comment on Roberts-Smith.

“I have no intention of prejudicing a matter that clearly is a legal matter, and that’s before the courts, and any comment would do so,” the PM told reporters in Canberra.

Roberts-Smith is a former SASR corporal who was awarded the Victoria Cross and the Medal for Gallantry, among others, for his service in Afghanistan. Around 39,000 Australian soldiers served in Afghanistan and 41 were killed.

His SASR colleagues are among those calling for him to become the first of Australia’s Victoria Cross winners to be stripped of the highest award for gallantry in battle.

Roberts-Smith has been financially supported by Australian billionaire Kerry Stokes whose media business Seven West Media is a rival of Nine Entertainment that published the articles that Roberts-Smith argued defamed him. In 2022, Mr Stokes, at Seven West Media’s annual general meeting, said: “Ben Roberts-Smith is innocent and deserves legal representation and that scumbag journalists should be held to account. And quote me on that.”