SEOUL (AFP) - Some of the six South Koreans sent home from North Korea Friday had entered the hardline communist state in search of a better life, a report said Sunday.
The six were taken into custody for questioning after being handed over - along with the body of a woman - at the border truce village of Panmunjom.
One of the six was the woman's husband, who had strangled her in an aborted suicide pact, the South's Yonhap news agency quoted "public safety authorities" as saying.
It said all six had entered North Korea illegally between 2009 and 2012 - either by jumping off a Chinese cruise ship in rivers along the North Korea-China border, or by walking across the rivers when they were frozen.
They said some of the men, whose ages ranged from 27 to 67, had posted pro-North Korea comments on the Internet under false names.
They "had fallen under the delusion that they would be treated well by the North Korean government when the communist country's official media introduced them by their pseudonyms", Yonhap said.
Some of them had only managed to find work in the South as day labourers due to family troubles, business failures or other hardships, and decided to defect in hopes their lives would improve in the North, it said.
While more than 23,500 North Koreans have escaped to the South from the North since the end of the Korean War in 1953, defections the other way are very rare.
The men told authorities they had been held and questioned in various detention centres across North Korea for up to 45 months before their repatriation.
They reportedly expressed disappointment and a sense of betrayal at the way they had been treated in the North, with some saying that they were not treated for health problems or allowed to leave their rooms in the detention centres.
The husband of the South Korean woman whose body was sent back reportedly said he and his wife had planned to commit suicide together. But the man, identified only as Lee, failed to kill himself after strangling his wife, authorities said.
Formal arrest warrants have been sought for the six before further questioning.
They could be charged with violating the strict National Security Law, which bans unauthorised contacts with the North, while Lee could also be charged with murder, authorities added.
The surprise return of the six was an apparent conciliatory gesture by Pyongyang at a time when North-South ties have been blowing hot and cold.
Tensions soared for months after the North's third nuclear test in February, but then appeared to enter a rapprochement stage that saw the two rivals agree to reopen their joint industrial park in Kaesong.
But the mood quickly soured again when Pyongyang cancelled a scheduled reunion last month for family members separated by the Korean War.
On Sunday, Seoul returned four North Korean fishermen and their boat after it drifted accidentally into southern waters.