KABUL, Afghanistan - A Christian aid group said Monday it had no plans to leave Afghanistan despite the massacre last week of 10 members of its medical team, six of them Americans.

Police were holding the lone survivor, an Afghan, for questioning, saying that he was not a suspect but that they had questions about his account of the horrific killings in northern Afghanistan.

The attack, far from the main theaters of the war in the east and south, underscored a widening insecurity in the region.

It was also the biggest assault on foreign Christians since the 2007 kidnapping of 23 South Korean missionaries by the Taliban in Ghazni province. Two male hostages were slain a month before the South Korean government negotiated the group's release.

The survivor of last week's attack, a driver named Saifullah who had worked for the humanitarian group for four years, was flown to Kabul on Sunday from Badakhshan province.

Also taken to the capital were the bodies of six Americans, two Afghans, a Briton, and a German, all gunned down after finishing a two-week medical mission treating Afghan villagers in the remote Parun valley of Nuristan province.

Five of the six American victims, including Glen Lapp, 40, a nurse from Lancaster, had been identified by Sunday. The sixth, named Monday, was Brian Carderelli, 25, of Harrisonburg, Va.

Carderelli's family said he was a photographer and was documenting aid work done by the International Assistance Mission and other groups.

Carderelli worked for the International School of Kabul. He went to Afghanistan in September and was compiling an album titled The Beauty - It's Not All War.

"He loved people and was particularly concerned for the poor," the family said in a statement Monday.

He was an active member of Covenant Presbyterian Church in Harrisonburg, said J.D. Patton, a family friend and an elder at the church.

The Taliban and a lesser-known insurgent group claimed responsibility for Thursday's killings, alleging that the group's members, most of them devout Christians, were spies and tried to convert Muslims. Some local officials suspect common criminals carried out the attack.

U.S. Embassy spokeswoman Caitlin Hayden said the FBI had opened an investigation into the deaths in cooperation with Afghan authorities.

During a news conference Monday, Dirk Frans, director of the International Assistance Mission, which organized the trip, insisted that conversion was not the team members' aim and that the Afghan government had given them permission to treat Afghans in the area.

"Our faith motivates and inspires us, but we do not proselytize," he said. "We abide by the laws of Afghanistan," which make proselytizing illegal.

Frans said "as things stand right now" his organization has no plans to leave Afghanistan, having operated in that country through the Soviet occupation of the 1990s, the civil war of the 1990s, and five years of Taliban rule.

But he said the losses had left the organization "devastated."

Team leader Tom Little, 62, of Delmar, N.Y., and Dan Terry, 64, had worked in Afghanistan for more than 30 years and had raised families there. As a sign of the group's commitment to the country, Frans said, the families of five of the eight foreigners had chosen to bury their relatives in Afghanistan.

The other Americans killed were Cheryl Beckett, 32, of Knoxville, Tenn., an expert in nutritional gardening and mother-child health, and Tom Grams, 51, of Durango, Colo., a dentist.

Also killed were Karen Woo, 36, a British surgeon; Daniela Beyer, 35, a translator from Chemnitz, Germany; and two Afghans, Mahram Ali, 51, a driver, and Ahmed Jawed, 24, a cook.

Another Afghan member of the team, ophthalmologic technician Saeed Yaseen, had left it before the attack.

Jawed's cousin, Maulana Korban Muhammed, remembered him as a polite young man who was the primary source of financial support for his wife, three young children, and extended family, the New York Times reported.

Rahim Majid, operations manager at IAM, said Ali, too, was a husband and father to three young children. One of his sons was paralyzed by polio and another's arm had been amputated. "He was the only person to care for his family," Majid said.

The lone survivor, Saifullah, had worked for IAM for four years and was described as a trusted colleague. He told authorities he was spared after pleading for his life and reciting verses from the Quran.

Gen. Mirza Mohammad Yarmand, chief of the criminal investigation division, said the driver was not considered a suspect but would probably be held for some time because he was the only witness and his presence was critical to the investigation. He refused to relate what the driver had told investigators in Kabul.

But inconsistencies have surfaced in various accounts attributed to Saifullah.

The Badakhshan police chief, Gen. Agha Noor Kemtuz, said there were many unanswered questions, chiefly why the gunmen spared Saifullah but killed the two other Afghans.

According to Kemtuz, Saifullah provided investigators with the following account:

"Little shouted, 'Who are you?' The attackers hit Little on the back of his head with a gun. He fell down and then they shot him. After that, they shot and killed Mahram and Jawed. Then they killed the other foreigners."