*Seoul (CNN) — New details have emerged about a US soldier (Private Travis King) who crossed into North Korea on Tuesday – but his exact whereabouts remain a mystery since the secretive country hasn’t said a word about the incident.

Court documents showed that Private King believed to be the first US soldier to cross into North Korea since 1982, had a history of assault, was facing disciplinary action over his conduct and was meant to go back to the US the day before the incident. An army official told CNN the private was set to be administratively separated from the US Army.

Details about how exactly King ended up on the North Korean side of the border remain unclear.

King had been on a tour of a border area as a civilian when he crossed the demarcation line.

His motive is also a mystery. King’s mother, Claudine Gates, told ABC she was “shocked” after being told by the US Army that her son had crossed into North Korea.

“I can’t see Travis doing anything like that,” Gates told ABC, adding that she heard from her son several days ago and he told her that he’d be returning to his base in Fort Bliss.

The US has been actively reaching out to North Korea to resolve the situation, but it has not yet heard back, a defense official said Wednesday. It is typical of North Korea not to respond to US outreach, the defense official added.

Adm. John Aquilino, who is in charge of US Indo-Pacific Command, said Tuesday that the US has had “no contact at this point” with North Korea in regards to King. Speaking at the Aspen Security Forum on Tuesday, Aquilino said King “made a run across the demilitarized zone in the Joint Security Area, was picked up by the North Koreans, and we’ve had no contact at this point.”

Source: US Soldier (Private Travis King) Who Crossed Into North Korea Has History of Assault and Detention | WATCH