KENOSHA, Wisconsin -- The mother of a U.S. soldier held in captivity in North Korea says her life has transformed into a "big nightmare" because what happened to her son remains a mystery.

Defense officials say U.S. Army Private 2nd Class Travis King, 23, ran across the demilitarized zone from South Korea into North Korea two weeks ago. On Monday, the Democratic People's Republic of Korea confirmed King crossed into their country, but both his whereabouts and his condition remain unknown.

U.S. Army spokesperson Bryce Dubee told ABC News that King, who was serving in South Korea, had spent 47 days in a South Korean jail after an altercation with locals in a bar; he was released in June. He was scheduled to return to Fort Bliss, Texas but bolted across the border on July 18 before he was to board a flight at South Korea's Incheon International Airport. U.S. officials say he was driven away in a van in North Korea, but they have no knowledge of his well-being.

Claudine Gates, King's mother, told ABC News in an exclusive interview late Wednesday that she doesn't believe her son would have risked his life by escaping across the heavily fortified area.

"Travis would not just go over the border like that. He's the type of kid he would've wanted to come home," she said. "He knew just going across the border is basically committing suicide."

Gates and her brother Myron both told ABC News that King was struggling months prior to his disappearance. They denied reports of drunkenness that led to his initial arrest by saying King was not a drinker and often isolated himself at family gatherings when alcohol was served. While overseas they said King often left them cryptic messages by phone or text. He sent YouTube links to songs they said served as coded messages to communicate to them that he was in a dark place. The unusual outreach even convinced them that they were either communicating with a different person entirely or that King was in trouble.

Claudine Gates recounted that one night she was awoken by a phone call from her son who repeatedly screamed into the phone, "I'm not the Army soldier you want me to be" before he hung up.

"When he first went to Korea, he was sending pictures home and he was just so happy. And then, as time went on, he just started fading away. I didn't hear from him anymore," she said.

The family said they have not heard from the White House or the US State Department. They have been in contact with US Senator Tammy Baldwin, from Wisconsin. They expressed strong doubt about the accuracy of what they are learning about King's disappearance but admit they don't know what happened to him that day.

"If he's in North Korea, his life is at jeopardy. All day, every day. We don't know how he's being treated. We don't know if he's eaten. We don't know if he's being tortured. We don't know if he's being interrogated. We don't know anything," said Myron Gates.

King is one of six children. On a recent night in Kenosha, almost 20 family members of all ages gathered, all dressed in black T-shirts with King's likeness on the front. Claudine Gates said her life "just changed in the blink of an eye" since his disappearance and the traumatic aftermath forced her to be temporarily hospitalized and put on anti-depressant medication.

"I was a very, very happy person. Any now, I just worry," To the North Koreans she only has one request: "Please, please send my valentine back home to me. I miss him so much," she said. "I just want to hear his voice."