Afghan President Hamid Karzai is accusing the United States of failing to cooperate in the probe of a massacre of 16 Afghan villagers, allegedly by a U.S. soldier.

President Karzai met with tribal elders and family members of those killed in Sunday's shooting spree in Kandahar province. He said Friday that the delegation he sent to investigate the killings did not receive the cooperation it expected from American officials.

Mr. Karzai lashed out, saying civilian casualties have been going on “for too long … and this is by all means the end of the rope here.” He said “this behavior can no longer be tolerated.”

The Afghan leader also questioned U.S. military claims that only one shooter was involved in the incident. Villagers say that more one U.S. soldier was involved in the attack in the Panjwai district, in which children were among those killed.

On Thursday, President Karzai met with U.S. Defense Secretary Leon Panetta in Kabul and demanded that NATO forces pull back from Afghan villages and relocate to their bases in the wake of the shooting spree.

The civilian lawyer for the U.S. soldier accused of carrying out the deadly rampage says his client was likely suffering from stress after witnessing one of his fellow soldiers sustain a grave injury.

Attorney John Henry Browne told reporters Friday the 38-year-old staff sergeant saw one of his comrades get his leg blown off a day before Sunday's massacre in Kandahar.

Browne says his client was also unhappy about being assigned a fourth tour of duty in a war zone. The soldier, a married father of two, had served three tours in Iraq, where he suffered a head injury and lost part of his foot. The lawyer says the highly-decorated soldier was told he would not be deployed to Afghanistan, but that changed “literally overnight.”

The suspect's identity has not yet been released and his family has been moved to a military base south of the western U.S. city of Seattle due to security concerns. Browne told reporters that family members said the staff sergeant never had any animosity towards Muslims. He was described as mild-mannered.

The soldier was flown out of Afghanistan to Kuwait late Wednesday. U.S. military officials said the suspect was moved to ensure “both proper pre-trial confinement and access to legal services.” Officials later said the soldier was being flown Friday to a maximum security prison at a U.S. military base in the state of Kansas.

Also Friday, U.S. military officials said a top U.S. commander in southern Afghanistan was in the path of an attack that coincided with Panetta's arrival Wednesday in Afghanistan. They had initially downplayed the incident.

Pentagon spokesman George Little told reporters traveling with the defense secretary that Major General Mark Gurganus, the U.S. commander in Helmand province, was part of a VIP delegation assembled to greet Panetta when an Afghan interpreter driving a stolen sports utility vehicle sped toward them.

Officials said the driver crashed into a ditch before emerging from the vehicle in flames. He later died of his injuries.

No one in the delegation was injured and Panetta's plane was safely diverted to another landing ramp at Bastion Air Field, a British base in Helmand.

Gurganus had declined to mention anything about the incident when speaking to reporters soon after it happened.

U.S. defense officials say they do not believe the Afghan translator knew that Panetta was in the arriving military aircraft