The family of a British adventurer have paid tribute to their "active and determined sister" after she was robbed and murdered while kayaking alone in the Brazilian Amazon.
Emma Kelty, a former headteacher from London, was "dearly loved" and "her strength will be sorely missed", her siblings said in a statement released by the Foreign Office.
The 43-year-old was last heard from on Wednesday, days after posting about her fears of being robbed or murdered in a jungle area in Brazil's remote north used for drug trafficking.
Ms Kelty was killed after being robbed and her body was thrown in the Solimoes River, head of the Amazonas state homicide division Ivo Martins said. Her body has not been found.
Three people were in custody, he added, including a teenager who had confessed to carrying out the killing with six other people.
In the Foreign Office statement, Ms Kelty's brothers Piers and Giles and her sister Natasha said: "Emma was an active and determined sister who challenged herself, latterly through her adventures on the Pacific Coast Trail, as well as in the South Pole and Amazon River.
"In a world that is today a much smaller place, the explorer in our sister found herself seeking ways to prove that challenges were achievable.
"We are extremely proud of our sister who was dearly loved by us all and her strength will be sorely missed."
Ms Kelty was 42 days into a 4,000-mile trip from the Amazon's source in Peru, through Brazil and to its mouth on the Atlantic Ocean, using a GPS tool, social media and blogging to let friends follow her progress.
Her last known location was around 150 miles west of the jungle city of Manaus, between the towns of Coari and Codajas.
The previous day she had tweeted about passing boats full of men with arrows and rifles, and the stretch of river she was attempting to travel is a known route for bandits and drug traffickers, local reports say.
Some of her belongings, including the kayak, were found by the Brazilian navy on Friday, Mr Martins had previously told local media.
A Foreign Office spokesman said on Tuesday: "We are supporting the family of a British woman following her death in Brazil and are in contact with the Brazilian authorities."
Olie Hunter Smart, an explorer who completed a similar route in 2015 and helped Ms Kelty plan her journey, said Coari was known to be a dangerous area.
Mr Smart, who is currently walking the length of India, said: "The Emma that I met was an incredibly brave and courageous person who lived life to the full.
"My thoughts go out to her close friends and family at this very sad time."
In a posting before the journey, Ms Kelty wrote that the adventure had four parts, and the third was "getting through the notorious drug baron and organ harvesting folks".
The self-confessed adrenaline junkie had only begun serious kayaking earlier this year, weeks after skiing a return solo journey to the South Pole.
Last year police chief Thiago Garcez, whose body has never been found, was said to have been murdered by drug-runners in the area where Ms Kelty disappeared.