(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.

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