PANJWAI, Afghanistan — Displaced by war, Abdul Samad moved his large family back home to this volatile district of southern Afghanistan last year. He feared the Taliban, but his new house was nestled near a U.S. military post, where he considered himself safe.

But when Samad, 60, walked into his mud-walled dwelling Sunday morning and found 11 relatives sprawled in all directions, shot in the head, stabbed and burned, he learned the culprit was not a Taliban insurgent. The suspected gunman was a 38-year-old Army staff sergeant.

The U.S. soldier is accused of killing 16 people in all as part of a bloody rampage that has tarnished Afghan-U.S. relations further and devastated Samad, a respected village elder whose tired eyes poured forth tears one minute and glared ahead in anger the next. Once a believer in the U.S. offensive against the Taliban, he now insists that the United States get out.

"I don't know why they killed them," Samad, a short, feeble man with a white beard and white turban, said as he struggled in an interview to come to terms with the loss of his wife, four daughters between the ages of 2 and 6, four sons between 8 and 12, and two other relatives.

"Our government told us to come back to the village, and then they let the Americans kill us," Samad said as he gathered outside the military post, known as Camp Belambay, with outraged villagers who came to support him.

They transported the bodies of Samad's family members, as well as the other victims, and the burned blankets that had covered them as proof of the awful crime that had occurred.

After years of war, Samad, a poor farmer, had been reluctant to return to his home in Panjwai, known in good times for its grapes and mulberries.

But unlike other displaced villagers who stayed in the city of Kandahar, about 15 miles away, and other places in the troubled province, Samad listened to the urgings of the provincial governor and the Afghan army. They had encouraged residents to return and reassured them that U.S. forces would protect them.

Back in his village, a collection of a few houses known as Najibian, Samad and his family had moved into a neighbor's house because his had been destroyed by NATO bombardments in the years of fierce battles.

His home in Panjwai and the other districts around Kandahar city — long the Taliban's heartland — had been a main hub of mujahedeen during the Soviet occupation. The districts became ground zero for the increase in force the Obama administration ordered at the end of 2009.

There had been little to no coalition presence in the area in the decade since the war began, and U.S. soldiers fought hard over the past two years to clear Taliban fighters from the mud villages such as Samad's that dot the area.

At the same time, they struggled to win the trust of the Afghans who live in the district, many of whom have proved wary of foreigners and fearful that the Taliban — which was pushed to the margins in many areas but still remained a forceful presence — would return some day and extract a heavy toll from those who cooperated with the Americans.

Some U.S. actions in the area also alienated villagers, such as the wholesale destruction of villages that commanders decided were too riddled with booby traps to safely control.

While the Taliban were pushed back for a while, villagers such as Samad say they are still active and describe what has become an intolerable life caught between the coalition forces and the Taliban while their meager vineyards and wheat fields are consumed.

"Taliban are attacking the bases, planting mines, and the bases are firing mortars and shooting indiscriminately toward the villages when they come under attack," said Malak Muhammad Mama, 50, a villager who now lives in Kandahar.

He said a mortar fired from the post a month ago killed a local woman, and that a roadside bomb hit a U.S. armored vehicle last week.

It was against this background that U.S. officials said the soldier left his post and walked south about a mile to Samad's village. Samad and his teenage son survived because they had been visiting the nearby town of Spinbaldak. When Samad returned home, neighbors were putting out the fire set on his family.

One of his neighbors, an elderly woman named Anar Gula, who had been cowering in her home, said she had heard an explosion, screaming and shooting as the soldier broke down the door of Samad's house and chased his wife and two other female family members from room to room before he shot them.

Two of the women and some of the children had been stabbed, she and other villagers said, and blankets had been laid over them and set afire — to hide the stab wounds, she said.

The soldier then circled back to another village, where he attacked the home of Hajji-Sayed Jan, 45, a laborer who had fled to Kandahar city three times during the years of fighting but who had brought his family back because he could not afford to live in the city, villagers said.

He survived because he was in Kandahar for the evening, but his wife, nephew, grandson and brother were killed. Farther on in the same village, the soldier entered a home and fatally shot Muhammad Dawoud, 55, a farmer, when he emerged from a room; his wife and children escaped to a neighbor's house.

Defense Secretary Leon Panetta said Monday that the staff sergeant returned to the post after the killings "and basically turned himself in, told individuals what had happened." Asked if the soldier had confessed, Panetta replied, "I suspect that was the case."

Panetta, who spoke to reporters on his plane en route to Kyrgyzstan, said an Afghan soldier first noticed that the sergeant was missing.

"He reported it, they did a bed check, they had prepared a search team to go out and try to find out where he was when they got news of what had happened, and this individual then turned himself in," he said.

The military would bring "appropriate charges" against the soldier, Panetta said, and the death penalty "could be a consideration."

He said the military still was struggling to understand a motive.

"We're not sure why, what the reasons were," he said.

But he called the killings "a criminal act" and said he had assured Afghan President Hamid Karzai that the soldier "will be brought to justice and be held accountable."

Echoing the public comments of Obama administration officials over the past 48 hours, Panetta said the United States remained committed to the more than decadelong war in Afghanistan and that the killings would not undermine the strategy or accelerate a planned drawdown of U.S. troops over the next two years.

"We've been through a series of challenging events over these last few weeks in Afghanistan," Panetta said, referring to widespread protests and violence over the burning of Qurans by U.S. forces.

He added, "We seem to get tested almost every other day."

Local elders and members of the provincial council gathered in Kandahar on Monday to denounce the attacks, decry their poor living conditions and question the value of the U.S. troop presence.

But while the mood in the south and in the capital, Kabul, was tense, there was less of the outright fury that brought thousands onto the streets after Quran burnings last month.

The Taliban posted gory photographs from the attack on their website, and photographs of the charred children circulated on many Afghan blogs and social networks, along with enraged anti-American comments.

The Afghan Parliament issued a statement saying its patience with the coalition forces was wearing thin. About 10 deputies from Kandahar walked out in protest of the killings.

"We urge the United States government to punish the culprits and put them on trial in an open court so that the rest of those who want to shed our innocent people's blood take a lesson from it," the statement said.

As for Samad, he said he was in too much despair to even think about how he would carry on with his life. But he said the lesson of the deadly shootings was clear: The Americans should leave.

Karzai called Samad after the killings, and the farmer, barefoot as he spoke plaintively into a satellite phone with district officials gathered around, told the president: "Either finish us or get rid of the Americans."

"We made you president, and what happens to our family?" he told Karzai. "The Americans kill us and then burn the dead bodies."

New York Times reporters Matthew Rosenberg, Sangar Rahimi and Elisabeth Bumiller contributed to this report.