The recording accompanies a video clip of the incident, shot with a helmet-mounted camera, which was not released. The evidence is part of a military court-martial in Bulford, England, in which three Royal British Marines are accused of killing the unidentified Taliban prisoner.
The defendants, identified as Marines A, B and C, have been charged in the death of the man, who was found lying in a field and injured in Helmand province after a helicopter attack.
During the trial the court heard the man was still alive when found by the British patrol. Marine A can be heard on the audiotape asking, "Anybody want to do first aid on this idiot?" Marine B loudly says "no." and Marine C offers to shoot the man in the head.
On the unreleased videotape, Marine A is seen walking toward the insurgent and shooting him at close range in the chest with a 9mm pistol, then saying, "Obviously this doesn't go anywhere, fellas. I just broke the Geneva convention," the British newspaper The Mirror reported Thursday.
After two weeks of evidence, the court-martial panel retired Thursday to consider their verdicts.