Australia’s Special Forces are facing more disturbing war crimes allegations surrounding their involvement in the Afghanistan war.

A U.S. Marine helicopter crew chief has detailed an incident wherein members of the Second Commando Regiment — an Australian Special Forces unit — appeared to have killed an Afghan prisoner. The Marine says Australian special forces shot and killed a bound Afghan prisoner after being told he would not fit on the U.S. aircraft coming to pick them up:

“And the pilot said, ‘That’s too many people, we can’t carry that many passengers.’ And you just heard this silence, and then we heard a pop. And then they said, ‘OK, we have six prisoners.”

“So it was pretty apparent to everybody involved in that mission that they had just killed a prisoner that we had just watched them catch and hogtie,” he added.

The U.S. Marine says that neither he nor any of his crew spoke about what had just happened.

“We were all being recorded on our comms. All of us were pretty aware of what we just witnessed and kind of didn’t want to be involved in whatever came next.”

He says that he later discussed the incident with his crewmates after returning to Camp Bastion, the former British military airbase in Lashkar Gah in Helmand Province, Afghanistan.

“This was the first time we saw something we couldn’t morally justify because we knew somebody was already cuffed up, ready to go, taken prisoner, and we just witnessed them kill a prisoner. This isn’t like a heat of the moment call where you’re trying to make a decision. It was a very deliberate decision to break the rules of war.”