The Pentagon has rejected claims made in an SBS Dateline report that the soldier who killed 17 Afghan civilians was not acting alone.
Staff Sergeant Robert Bales, 38, is said to have walked out of his base in the southern province of Kandahar in the early hours of March 11 and mounted a massacre in two nearby villages, with many of his victims women and children.
Dateline Video Journalist and Presenter Yalda Hakim was the first journalist to visit the village where the killings took place, with her report making international news.
Witnesses said a group of Americans, perhaps 15 or 20, were also present.
It has also been claimed that Bales returned to base, after the first attack on the village and spoke with other soldiers, before heading back to the village.
Bales' lawyer John Henry Browne denied the claim.
"That is an allegation. Of course it's not proof of anything. And obviously I can't tell you what my client remembered or doesn't remember, other than saying that he has memory problems about everything that happened that night," Mr Brown said.
Afghan President Hamid Karzai has also cast doubt that Robert Bales acted alone.
Witnesses have told Mr Karzai's Chief investigator that helicopters were present from the very beginning of the shooting.
Attorney Browne said he will cite Post Traumatic Stress Disorder (PTSD) to defend Bales.
Bales, who is being held at the Fort Leavenworth military base in Kansas, has been charged with 17 counts of premeditated murder, as well as six counts of assault and attempted murder in connection with the massacre.
Browne claimed there was a lack of evidence from the scene.
"It's not a traditional crime scene. There is no crime scene. The military has not even been back to the villages where this allegation stems from. They haven't been back there," Browne said.
"So there's no crime scene, there's no DNA, there's no fingerprints, there's no confession. It's -- you know, the Afghan people traditionally, I understand, and understandably, bury their dead very quickly.
"So it's going to be a tough case for the prosecutors," he added.
The killings have put further strain on the already difficult relationship between Kabul and Washington, after the burning of Korans by American soldiers in mid-February triggered deadly anti-US protests.
TRANSCRIPT of Yalda Hakim's story Anatomy of a Massacre
INTERVIEW WITH YALDA - Yalda Hakim explains to SBS Radio's World News Australia how she was able to get such unprecedented access to the massacre investigation.
Watch Yalda Hakim's earlier interview with President Hamid Karzai
Watch this report on YouTube:
