THE family of a missing woman has shared an eerie final video, showing her waving from a boat before vanishing on a yoga retreat.

Nancy Ng, 29, disappeared last month while traveling in Guatemala – prosecutors think she drowned in a kayaking incident but her family says that conflicts with information their attorney gave them.

The FBI said it would offer resources to Guatemalan authorities in an effort to find Ng.

The US State Department has also been in contact with local officials and is keeping an eye on the investigation.

“My dad, he … I know this sounds terrible but he keeps his phone next to him at night,” Nancy’s sister, Nicky Ng, told ABC News in an emotional interview.

“He’s hoping for a ransom call, you know, something that will prove that Nancy might still be alive and that she’s out there, that she’s waiting for us to find her.”

Ng’s family said the last known video of the young woman was shared with searchers, and showed her waving at the camera while kayaking on October 19 – just before she disappeared.

Her family said she went on a kayaking excursion in Lake Atitlán but did not return.

The Guatemalan prosecutor’s office said Ng was traveling with a US-based tour group.

She went on the kayaking trip, according to a woman who accompanied her on the venture.

The woman said the group advanced “approximately 2 kilometers deeper into the lake, where the missing woman tells [the witness] she wants to swim and that is when she drowns.”

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It’s unknown why it took the witness and the tour group 24 hours to report the incident to authorities.

Ng was last seen about half a mile away from the shore, according to reports from local fire and rescue officials.

Her kayak was found some time later but there was no sign of the woman.

Ng was described by her family as a loving person who is full of life.

She works with special-needs children in the Alhambra Unified School District in Southern California.

“Please help us bring Nancy home,” said her mother, Stephanie Li.

A private search team led by Black Wolf Helicopters owner Chris Sharpe has been hired by the family.

“We’ve searched 99% of the lake – that’s was with helicopters, drones, boat crews,” said Sharpe.

The difficult terrain along with limited information has made the search complicated, he added.

This was Ng’s second year going to the retreat, said her family.

“There are people that witnessed what happened, within the group, that haven’t come forward,” said Nicky Ng.