Lurid and bizarre details emerged: that Mr. Roberts-Smith had hired a private investigator to spy on a girlfriend at an abortion clinic after they had agreed to end her pregnancy; that he had been accused of burying evidence in a child’s lunchbox in his backyard; and that he had poured gasoline on his personal laptop and set fire to it.

The case contained two centerpiece allegations. In 2009, the newspapers said, two Afghan men were discovered hiding in a tunnel at a compound and taken prisoner. Mr. Roberts-Smith, the newspapers reported, killed one of the men, who had a prosthetic leg, and ordered a more junior soldier to kill the other as a form of initiation. Mr. Roberts-Smith then took the prosthetic leg back to Australia, the newspapers said, and encouraged other soldiers to use it as a novelty drinking vessel.

The newspapers also said that, in 2012, Mr. Roberts-Smith kicked an unarmed, handcuffed Afghan farmer off a cliff and that a colleague then shot the man dead as Mr. Roberts-Smith watched.

Mr. Roberts-Smith denied that any Afghans had been found in the tunnel in 2009. In the other case, he said, the man was a Taliban scout, not a farmer, and had been killed lawfully in combat, not after being kicked off a cliff.

The newspapers had to prove it was more likely than not — rather than beyond a reasonable doubt, as in a criminal case — that Mr. Roberts-Smith committed war crimes.