Updated

The cousin of a Colorado woman who disappeared while hiking alone in Nepal more than two months ago believes the missing hiker is still alive.

Although the family of missing Aubrey Sacco knows little about her whereabouts -- and locals there refuse to talk -- her cousin, Amanda Dewbray, told FoxNews.com they aren't giving up hope.

"We have to believe that. We have to keep searching. We're determined to find her," Dewbray says. "Being that we haven't found a body, we don't have any evidence that she was murdered."

The 23-year-old of Greeley, Co., last communicated with her family via e-mail on April 20, saying she would finish her trek in the Himalayas around April 30, Dewbray said.

But Sacco, who last updated her blog on April 15, hasn't been heard from since.

Dewbray said the family became worried because "that's not like her to not check in or not call." Sacco was scheduled to return home at the end of May.

Sacco's father, Paul Sacco, who went to Nepal last month to look for his daughter, said he recovered her laptop computer and journal from the hotel where she was staying. Dewbray said Sacco's brother and a Colorado man originally from Nepal went with the father.

But the group returned with little information because locals in Nepal claim they know what happened to Sacco but refuse to give details.

"Out of the search, we don't really have any evidence. ... The feedback they've given us is that they know what happened and they won't tell," Dewbray said. "Another woman even said, 'You'll never see her again."

In an interview with Fox 31, Paul Sacco said he thinks the local villagers aren't talking because they fear retribution from local law enforcement.

"We have the feeling that she's being held, you know, or detained," the woman's mother, Connie Sacco, said in an interview with Fox 31 in Denver.

The FBI announced Sunday that it is helping the U.S. State Department in an investigation into Sacco's disappearance. Denver FBI spokeswoman Cathy Wright said they aren't giving updates at this time and referred to the state department.

Calls from the department were not returned.

Sacco started her trip in Sri Lanka studying eastern philosophy and alternative healing, Dewbray said. From there, she went to India to study yoga and meditation and teach students English and American school games.

Dewbray, who made a Facebook page as part of the search for Sacco, said the family tripled the reward amount.

"There are people that know what happened to her," Dewbray said. "How do we get them to talk? ... If their government could ensure their safety in the country that they could talk but I don't know if that's possible."

Click here to read more on this story from Fox31.com

The Associated Press contributed to this report