A Christian charity group has said it believes militants, not robbers, killed 10 members of its medical team, including British doctor Karen Woo, last week in a remote area of northern Afghanistan.
In the first days after the attack, the group's leaders said they suspected the team was set upon by robbers, despite a Taliban claim of responsibility. Local police also said they suspected a criminal motive.
But Dirk Frans, director of the International Assistance Mission, said that while Afghan and US authorities are conducting official investigations into the killings - of Londoner Dr Woo, 36, six Americans, two Afghans and a German - the group has done research of its own to learn more about who might be responsible.
"Our own research suggests that the murders were not a robbery," he said. "We are now working on the assumption that the attack was an opportunistic ambush by a group of non-local fighters."
Mr Frans said the members of the team were attacked as they made their return trip towards Kabul from their mission to dispense medical care to villagers in remote Nuristan province. They were set upon by gunmen as they got out of their vehicles to take a rest after crossing a swollen river.
The account squares with that given by the lone survivor, the team's Afghan driver Safiullah, whom Mr Frans said has been released by Afghan authorities after questioning.
According to Safiullah, who goes by one name, an Afghan man in the area offered to help the team as it was trying to cross the river. Two members of the team, including leader Tom Little, an optometrist from Delmar, New York, who had worked in Afghanistan since the late 1970s, rolled up their trouser legs and waded in to find a spot shallow enough for the vehicles to ford the river.
After successfully crossing, the team stopped to take a break in a forested area at the side of the road, which ran through a narrow valley. They wanted to get ready for their long journey back though Badakhshan province and on to Kabul.
The Afghan man who had offered to help the group left. Then came the attack. The gunmen rushed in, firing bullets over the medical team members' heads.
Safiullah told investigators he believed the lead gunman was Pakistani because he yelled "Jadee! Jadee!" - a word used in several regional languages that means "hurry up". It is more commonly used in Pakistan and India than Afghanistan. He said all the attackers understood Dari and Pashto, the two main languages spoken in Afghanistan, but conversed in Pashaye, a local dialect used only in parts of the north-east corner of Afghanistan.