(CNN) - An American tourist who is legally blind and eventually will totally lose her sight was last seen more than a week ago on a trail near a small village in Peru, her brother said Saturday.
The new witness information puts Carla Valpeoz, a 35-year-old social activist and experienced traveler from Detroit, in Pisac on December 12, Carlos Valpeoz said in an email to CNN.
He wrote that three people -- a bus driver, a trail employee and an archeologist -- each saw his sister, who has very low vision and uses a cane when she travels. They said she was by herself.
Previously police had said a cab driver who dropped Valpeoz off on the morning of December 12 near an area where people can catch buses to other towns was the last person to see her.
The new witnesses say Valpeoz got off a bus in Pisac near the Urubamba River, that she went on a hiking trail to an Inca archaeological site, and that she was walking alone, according to her brother.
He said authorities have said they are going door to door in Pisac, which is about 35 kilometers (22 miles) northeast of Cusco and 1,100 kilometers (683 miles) from the capital of Lima. They are also bringing in expert mountaineers, search dogs and drones, the brother said.
"Carla is a very determined person, a humanitarian in her community, a leader devoted to life, to travel and immersing herself," he said earlier this week. "Since an early age, our family has prepared her for when she would lose her sight and that's why she wants to see so much."
He added that his sister would not put herself in a position that was dangerous. She had been in Peru to attend a wedding and do some exploring.
CNN reached out to the US State Department and the FBI for comment on the latest details of the search, but didn't receive an immediate response.
The State Department said previously it has no greater priority than the safety of US citizens abroad, and that they're aware of media reports about the missing woman, but couldn't comment further.
She wants to bridge cultures
In videos posted last year to YouTube, Carla Valpeoz said she was diagnosed with optic nerve atrophy when she was 10. The American Association for Pediatric Ophthalmology and Strabismus says the condition is "mild to severe damage to the optic nerve that can adversely affect central vision, peripheral vision and color vision." There is no treatment that can reverse optic nerve atrophy, it says.
Valpeoz says on one video: "I want to create a platform and I want to bridge communities of cultures ... so we can learn to work together."
She says she has traveled to many parts of the world to see how diverse cultures live. Her brother said her travels had been to Egypt and South America, and that she also has lived in Papua New Guinea and Yemen.
"She has had a challenging life but she doesn't fall in the category of just being a blind person and wants to experience the world before she can't see anymore," he said. "She has always had a great heart. She sees the world in a positive light."
In another video she says she is writing a book about her perspective on life.
Valpeoz works at the Arab American National Museum in Dearborn, Michigan, according to a tweet from the group.
She had been to Machu Picchu
While in Peru she had ascended Huayna Picchu, overlooking the famed Machu Picchu with a group of people, her brother said.
They got back to Cusco at about 10 p.m. December 11 and she went out with people from the group to a club. She and another woman she met that day returned to their hostel around 4 a.m. and Valpeoz slept in a room with nine other people.
She left the hostel in a cab at about 9 a.m. December 12, according to surveillance video. She sent her last message on WhatsApp at about that time, her brother said.
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