One of the drivers of a convoy of medical workers shot dead as they travelled through a remote area of Afghanistan has been arrested.
British doctor Karen Woo, 36, six Americans, one German and two Afghan translators were ambushed by gunmen.
The Taliban said it carried out the killings, but local officials blamed armed robbers for the attack.
The team was working with a Christian charity providing eye care. Dr Woo was planning to marry later this month.
Her fiance, Mark "Paddy" Smith, told the Mail on Sunday that they had met in November last year and that their relationship "just made sense".
Speaking from Afghanistan, where he works, Mr Smith said: "Karen grabbed life by the horns. She went to one of the most dangerous places in Afghanistan just to help people. That was the sort of girl she was. She was focused and professional.
"It was one of those crazy relationships. Nothing is normal in Afghanistan, but when we met it just made sense. You know when something is right and this was just right."
Dr Woo's brother David told The Sunday Times: "She was a lovely, vibrant and energetic woman, determined to get the most out of life.
"She and Mark just clicked. She said he was the one. Their long-term plan was to come back to the UK and start a family together."
Team leader Tom Little, an optometrist from Delmar, New York, was among the dead. He had been working in Afghanistan for about 30 years.
He had supervised a network of eye hospitals and clinics around the country largely funded through private donations.
Mr Little's friend, David Evans, of the Loudonville Community Church, New York, paid tribute to him.
"He was a remarkable man, and very committed to helping the people of Afghanistan. They raised their three girls there. He was part and parcel of that culture," said Mr Evans.
The bodies of the medical workers have been taken to a hospital in Kabul, to be formally identified.
A spokesman for Christian charity International Assistance Mission (IAM) said the team had been working for the past two-and-a-half weeks in the province of Nuristan.
Their bodies were found in the north-eastern province of Badakhshan on Friday.
Badakhshan, a mainly ethnic Tajik region bordering Tajikistan, is one of the few Afghan provinces not to have been controlled by the Taliban before the US-led invasion of 2001.
The BBC's Quentin Summerville said it has long been regarded as a safe area, although locals have complained about the growing threat from insurgents.
Taliban spokesman Zabihullah Mujahid claimed the group were found in possession of bibles translated into Dari and had been killed because they were Christian missionaries.
Dr Woo, from London, is not the first Christian aid worker to to be killed in Afghanistan. In October 2008, Gayle Williams, a dual British and South African citizen, was killed by two gunmen as she walked to work in the capital, Kabul.
John Dempsey, who works in Kabul for the U.S. Institute of Peace, says Christian groups will have to consider their position.
He said: "I don't think they necessarily need to withdraw but I certainly think after what's happened earlier this year, and of course today's attack, they have to reassess what it means to be a Christian organisation in a country where they often are the ones singled out and targeted, and there may be measures they could take to improve their security for themselves.
"So I think there is still room for Christian organisations to operate in many parts of the country, but they'll have to be careful in terms of selecting where those might be."
IAM's executive director Dirk Frans said the group was in shock over the deaths.
He called the Taliban's assertion "very strange" adding that unusually, it took the group two days to make the statement instead of claiming responsibility straight away.
He told the BBC: "We are Christians but we work under the laws of Afghanistan and those laws do not allow us to proselytise.
"The chief of police said it was basically robbery because nothing of value was left on the bodies. They are not missionaries."
He added that the group had no intention of withdrawing from the country where it had worked for more than 40 years.
"The situation now is not paradise but some staff say it is not as bad as the early 90s."
Dr Woo's friend Firuz Rahimi said she was "a brilliant person to work with".
He and Dr Woo both worked with another aid organisation, Bridge Afghanistan.
Ahead of the trip on which she was killed, Dr Woo had written a letter to likely benefactors, telling of the expedition's aims.
She wrote in the letter: "The trek will not be easy; it will take three weeks and be done on foot and with packhorses - no vehicles can access the mountainous terrain.
"The expedition will require a lot of physical and mental resolve and will not be without risk but, ultimately, I believe that the provision of medical treatment is of fundamental importance and that the effort is worth it in order to assist those that need it most."