Gone: David Sneddon was 24 years old when he disappeared during a solo hiking trip in China

Twelve years ago, a BYU student hiking alone in China went missing and authorities concluded that he likely fell off the trail and drowned in the river below.

But the family of David Sneddon, who would be 35 today, never bought the story and are now convinced there's a chance he was kidnapped and taken to North Korea.

On Tuesday, Utah lawmakers Rep. Chris Stewart and Sen. Mike Lee appeared before Congress with a proposal for the State Department to investigate Sneddon's disappearance, with new emphasis on the theory that he may have been abducted by North Korean agents.

'The first and most important responsibility of the United States government is to ensure the safety and freedom of the American people at home and abroad,' Lee said.

'This includes investigating all plausible explanations behind David’s disappearance, and leaving no stone unturned in trying to return one of our brothers to his family.

'At the time of his disappearance, David had his whole life ahead of him. But in August 2004 it was tragically cut short. The Sneddon family deserves to know why.'

The proposal was co-sponsored by the entire Congressional delegation from Utah.

New efforts: On Tuesday, Utah Rep. Chris Stewart and Utah Sen. Mike Lee put forth a proposal to Congress, asking the State Department to look into Sneddon's disappearance. Sneddon is pictured left and pictured right a poster is displayed following his disappearance

Without a trace: When he disappeared in August 2004, Chinese officials concluded that Sneddon likely fell off a trail and fell into a river and drowned in Yunnan Province

Last seen: Above, the Tiger Leaping Gorge in Yunnan where Sneddon is believed to have done missing in 2004

Sneddon's parents were always suspicious of the Chinese government's conclusion that their son likely fell off a hiking trail and drowned in a river in western China, but they never considered a possible abduction by North Korea until hearing the theory from a former high-level U.S. official in 2011.

Sneddon certainly could have been useful to the Kim regime since he was fluent in Korean from spending two years as a Mormon missionary in South Korea.

The North Korean regime is well known for kidnapping foreigners, though they predominantly abduct other Asian peoples.

Several questions about Sneddon's disappearance have also gone unanswered, such as why some witnesses reported seeing him when he had already finished his hike and why his body and none of possessions were found.

Multi-lingual: Sneddon could have been valuable to the North Korean regime since he was fluent in Korean from his years working as a missionary in South Korea

The summer of his death, Sneddon was 24 years old and had just finished his third year at BYU. He traveled to China when school let out to study Mandarin in Beijing, before hiking in western China for a few weeks.

The last time his parents heard from him, Sneddon was getting on a bus to take him to Yunnan province to hike the Tiger Leaping Gorge, a highly-trafficked trail on the Jinsha River that usually takes about two days to complete.

He was last seen leaving a Korean restaurant in Shangri-La, a town not far from the trail, on August 14.

At the end of his hiking trip, he was set to fly out of China to Seoul, South Korea where his brother lived. His parents reported him missing on August 26, when he didn't show up at the airport.