Nancy Ng hasn't been seen since Oct. 19. It is believed she went out on a kayak with a yoga group on Lake Atitlán that day, but many of the witnesses who may have more information about her activities reportedly have not been cooperating with investigators.
Lee and Elaine Beal, owners of Kayak Guatemala, spoke with ABC News and said the yoga group consisted of 10 people, including Nancy.
They set out on the water that morning. The couple even shared a photo one of their employees took of the group.
"When the group returned, there were only eight that returned, but we could see in the distance, a distance of about 100 yards, two single kayaks," recalled Lee.
Those two kayakers were Nancy and another woman.
"We watched them as they continued paddling until we lost sight of them," he said. That's when a distress signal was called in.
"I witnessed the survivor being ushered up the steps with the yoga instructor. She was clearly distressed, and they didn't say a word to us," said Elaine.
However, there was no sign of Nancy.
Lee mentioned no one in the remaining group appeared to be interested in speaking with anyone.
"It was almost like, immediately clamming up and like, 'We're not going to say anything,'" said Lee.
The Beals said they called the group's hotel the next morning because they hadn't been paid only to learn they were gone.
"I just don't understand that part of leaving within 8 hours, 12 hours of the accident," said Elaine.
ABC News has learned the Guatemala Attorney General's Office hasn't been able to interview the woman who was with Nancy or the tour guide because the group left the country. They've requested international assistance to speak with them, but are still waiting to hear back.
Nancy's family hired a private search team, who said they scoured much of the area of the lake by air and underwater but found no sign of her.
The Guatemalan government said Wednesday 95% of the lake was searched and those efforts have now halted.
Guatemalan government prosecutors believe she went swimming and drowned.
Family of SoCal woman who vanished during Guatemala yoga retreat speaks out; FBI involved in search
Nancy's family sent a statement to ABC News, saying "Our family has tried to contact the witness many times over the last three weeks but she will not speak with us. The police report we received did not include a direct statement from her either. Her silence has hindered our search efforts and left us in the dark about what happened to Nancy. We don't know which nightmare scenario to believe."
Nancy worked with special-needs children in the Alhambra Unified School District. They describe her as a person who is loving and full of life.