SEOUL, South Korea - An 85-year-old U.S. veteran being held in North Korea spent his war years there in one of the Army's first special forces units, helping a clandestine group of Korean partisans who were fighting and spying well behind enemy lines.

South Koreans who served with Merrill Newman, who is beginning his sixth week in detention, say their unit was perhaps the most hated and feared by the North and his association with them may be the reason he's being held.

"Why did he go to North Korea?" asked Park Boo Seo, a former member of unit known in Korea as Kuwol, which is still loathed in Pyongyang and glorified in Seoul for the damage it inflicted on the North during the war. "The North Koreans still gnash their teeth at the Kuwol unit."

Some of those guerrillas, interviewed this week by the Associated Press, remember Newman as a handsome, thin American lieutenant who got them rice, clothes and weapons during the later stages of the 1950-53 war, but largely left the fighting to them.

Newman was scheduled to visit South Korea to meet former Kuwol fighters following his North Korea trip. Park said that about 30 elderly former guerrillas, some carrying bouquets of flowers, waited in vain for several hours for him at Incheon International Airport, west of Seoul, on Oct. 27 before news of his detention was released.

Newman appeared over the weekend on North Korean state TV apologizing for alleged wartime crimes in what was widely seen as a coerced statement.

Park and several other former guerrillas said they recognized Newman from his past visits to Seoul in 2003 and 2010 - when they ate raw fish and drank soju, Korean liquor - and from the TV footage, which was also broadcast in South Korea.

Newman's family has not been in touch with him, but he was visited at a Pyongyang hotel by the Swedish ambassador, his family said in a statement, and he appeared to be in good health, receiving his heart medicine and being checked by medical personnel.

Newman served in the U.S. Army's 8240th unit, also known as the White Tigers, whose missions remained classified until the 1990s.

Retired Col. Ben Malcom said he served in the unit during a different period than Newman, and didn't know him. But he later wrote a book about their work detailing how the U.S. supplied weapons, ammunition, food, and American advisers to an anticommunist guerrilla force in North Korea. He said some were outfitted with North Korean military uniforms complete with weapons and identification cards to work as spies. Others were trained as paratroopers.

Malcom said his openness about the unit's work during the war, including a book, a History Channel documentary and many interviews, would preclude him from even considering visiting North Korea.

"I would never go back to North Korea," he said. "They know me."