(CNN) -- South Korean fisherman Jeon Wook-pyo set out on a boat in the Yellow Sea more than 40 years ago -- and didn't get home till Friday.
Jeon's return to his family in Seoul from North Korea raises more questions than answers, and underscores the larger issue of alleged abductions by North Korea.
Jeon, now 68, escaped last month from North Korea to a country which has not been identified publicly, where he wrote a letter to South Korean President Park Geun-hye, appealing for help to return to Seoul.
"I took a chance to escape the North because I had a growing wish to spend the rest of my life with my relatives and brothers at home," he wrote Park, according to South Korea's Yonhap News Agency.
Jeon reunited with his family in the South Korean capital on Friday after undergoing questioning by South Korean officials, a Unification Ministry official told CNN.
Jeon and two dozen other fishermen were abducted from two boats off South Korea's western coast on December 28, 1972; none of the others has returned, Yonhap said.
South Korea was not aware that Jeon had been abducted by North Korea until 2005, when a photograph from 1974 surfaced showing him at an indoctrination camp in North Korea with several other abducted South Korean fishermen, according to South Korea's Chosun Ilbo newspaper.
Abductions have long been a source of conflict between the Koreas, who have maintained tense relations since their 1950-53 conflict. The Korean war ended in an armistice, not a peace treaty, meaning the two sides are still technically at war.
South Korea has accused North Korea of abducting its citizens for intelligence-gathering or propaganda purposes. Pyongyang has denied holding any South Koreans against their will.
Just how many South Koreans may have been abducted is unclear, said Ron Redmond, a spokesman for the United Nations Commission of Inquiry on Human Rights in North Korea.
"It's a difficult thing to assess, because lots of times, these cases don't turn up for a year," he said from Geneva. "Nobody knows what happens; they disappear."
The South Korean government said that, since the armistice, about 3,500 of its citizens have been abducted by North Korea, most of them at sea during the 1960s and 1970s, Redmond said.
Though most have been freed, the government says that the whereabouts of about 500 are unknown, he said.
Other countries, including Japan, have also accused North Korea of abductions. Tokyo has cited 17 cases of Japanese nationals abducted by Pyongyang, according to Giuseppe Calandruccio, also with the U.N. commission.
"There are many other cases where there are suspicions, but nobody can prove it," he said.
Last month, more than 40 witnesses -- some of them recently arrived from North Korea -- testified before representatives from the U.N. inquiry commission in Seoul, and they detailed horrific abuse at the hands of their captors. A report from the commission is due in March.
One of those who testified was Jeong Kwang Il, a North Korean defector once worked for a North Korean trading company that he said dealt with China and South Korea.
That ended abruptly in 1999, when he was arrested by government security agents, he said. "These people were beating me with clubs, and they said I should confess that I am a spy. But I told them. 'I'm not a spy.' But they kept beating me -- for two weeks."
After undergoing "pigeon torture," in which he was hung upside down with his hands cuffed behind his back, he confessed to what he told the commission he had never done.
"I could not endure this any more so I confessed that I was given a spy's job from South Korea," he said. "I had given up."
Jeong said he was then taken to a political camp, where he spent three years before he was released to discover that his home was no longer where it had been, and he could not find his family.
"I felt betrayed," he said. "I decided that I was done in North Korea."
After a year-long escape route that took him through China, Vietnam, Cambodia and Thailand, Jeong arrived in South Korea in 2004, where he has started a new life, but not forgotten the old one.
"Even if they give me a lot of money, I will not go back to that country," he vowed.
The U.N. Commission of Inquiry on Human Rights in North Korea was established in March by the U.N. Human Rights Council to investigate "systematic, widespread and grave violations of human rights in North Korea."
CNN's Paula Hancocks contributed to this report.