Updated 6:58 PM ET
(CBS/AP) KABUL, Afghanistan - A U.S. military official says probable cause has been found to keep holding an American soldier suspected in a shooting spree that killed 16 Afghan civilians.
The bloody incident has fueled anti-U.S. sentiment in a country weary of the decade-long war.
The soldier, who has not been named, is accused of leaving a U.S. base in Panjwai district of southern Kandahar province and gunning down the Afghan civilians, including nine children and three women, in the middle of the night between Saturday and Sunday.
Col. Gary Kolb, a spokesman for the U.S.-led military coalition in Kabul, says a 48-hour probable cause assessment has been completed and that the service member continues to be confined.
U.S. Secretary of Defense Leon Panetta has said that the soldier could face capital punishment.
CBS News national security correspondent David Martin reported of new information that is at odds with the initial version that the soldier simply turned himself in. According to this new information, when it was discovered he was missing from the base, a search party complete with helicopters was sent looking for him and found him crawling through an orchard as if he was trying to sneak back on to the base undetected. When he was taken into custody, he invoked his right to remain silent and demanded a lawyer.
The U.S. command in Kabul has announced there is probable cause in continuing to hold him while lawyers prepare charges against him, Martin reported. That is expected to take two weeks or less, and when charges are brought, his name will be publicly released.
Martin added that there will undoubtedly be a full psychiatric evaluation in this case as well and a reconstruction of the soldier's three combat tours in Iraq to determine to see if he is suffering from post traumatic stress or traumatic brain injury. There are also reports he was going through marital problems, which would not be uncommon for someone on his fourth combat tour. And there is even some indication that alcohol was involved, although it is not clear if it was detected on his breath when he was taken into custody or found later in his locker room.
The incident has also added to pressure in the U.S. to get out of Afghanistan more quickly.
Panetta, speaking to reporters on a plane traveling to Kyrgyzstan, said the military withdrawal was still on schedule to finish by 2014. Panetta said he was awaiting plans from Gen. John Allen, the top commander in Afghanistan, to bring home the remaining 23,000 U.S. troops sent to Afghanistan during the 2009 surge. Those forces are due to leave by the end of September, dropping the U.S. presence in the country to 68,000 troops.
On Tuesday, President Barack Obama, who has said that the U.S. strategy in Afghanistan would not change in light of the killings, issued his strongest condemnation of the shootings.
"The United States takes this as seriously as if it was our own citizens and our own children who were murdered," Obama told reporters in Washington.
"I can assure the American people and the Afghan people that we will follow the facts wherever they lead us, and we will make sure that anybody who was involved is held fully accountable with the full force of the law," he said.
Nine of the 16 civilians killed in Balandi and Alkozai villages were children and three were women, according to the Afghan president. Some of their bodies were burnt after they were killed.
A delegation of top Afghan officials investigating the killings visited Balandi on Tuesday to collect information from villagers, but Taliban insurgents opened fire on the visitors.
The shooting began as Qayum and Shah Wali Karzai, two brothers of Afghan President Hamid Karzai, left a memorial service for the victims. Karzai's brothers and other top Afghan officials in their delegation escaped in their cars unharmed from the ambush.
But one Afghan soldier was hit in the head almost immediately and died, while two other Afghan army personnel were wounded in the 20-minute firefight that ensued in one of the two villages where the killings had occurred two days before.
The gunbattle came as images of the aftermath of Sunday's killings spread across the country, and the public reaction -- which at first seemed surprisingly muted -- began to build.