A Special Air Service Regiment trooper on his first deployment to Afghanistan was pressured to execute an elderly, unarmed detainee by fellow higher-ranking soldiers as part of a "blooding" ritual, according to defence insiders who were witnesses at the scene.

And on the same mission, another man with a prosthetic leg was killed by machine-gun fire. His plastic leg was souvenired and later taken back to SAS headquarters in Perth to be used as a novelty beer drinking vessel.

This man, whose right leg is prosthetic, was among Afghans killed in 2009 in incident that involved alleged war crime. We have chosen to blur the image.

The summary execution of the elderly detainee on Easter Sunday, 2009, is one of several incidents involving a rogue SASR team operating in Afghanistan which has been uncovered by a Fairfax Media investigation and corroborated by special forces insiders.

The grey-haired, bearded Afghan man executed by the "rookie" was, according to some SASR members, a suspected Taliban member, but at the time presented no threat to Australian soldiers. The newly deployed soldier allegedly shot the man after being prompted by two more senior soldiers, one of whom was earlier overheard proclaiming a need to "blood the rookie".