SEOUL, South Korea — It was sad enough when the bodies of Han Sung-ok and her 6-year-old son were found in their $74-a-month apartment in Seoul in July, two months after they had died.
But the story became national news after it emerged that Ms. Han, 42, was a North Korean who had fled famine in her homeland, and that the two had died alone and impoverished in one of Asia’s richest cities.
Their bodies were so decomposed that the cause of death could not be determined, according to the authorities. But several South Korean news outlets have reported that they died of starvation, and officials have not disputed those reports. The news channel that broke the story last month quoted an unidentified police officer as saying that there was no other possible explanation.
The deaths have been a shocking reminder of the hardships faced by many North Koreans in the South, as they try and sometimes fail to adjust to a radically new life. Since the news became public, thousands have visited a mourning station built for Ms. Han and her son, Kim Dong-jin, in central Seoul, laying white chrysanthemums in front of portraits of them.
The most emotional visitors were other North Koreans and their supporters, hundreds of whom came from across the country on Saturday to attend a funeral ceremony for the mother and son. Speaker after tearful speaker apologized for not protecting them from the prejudices, indifference and ostracism that many North Koreans say they experience in the South.
“I am still struggling to understand this: She escaped a famine in North Korea — only to starve to death in the heart of South Korea, where there is so much food that going on a diet is its biggest fad,” said Heo Kwang-il, who leads a North Korean defectors’ organization.
Not much is known about Ms. Han’s life in either Korea. But she appears to have become increasingly isolated and despondent in her last months, though help for her and her son was just a few hundred yards away at a district government office.
She first arrived in South Korea in 2009, according to government records. Like all defectors from the isolated, totalitarian North, she went through 12 weeks of mandatory classes, learning basic skills like using a credit card and driving a car.
The government provides North Korean refugees with low-rent apartments, welfare payments and free health care and job training. But many struggle to make the transition from the North’s highly regimented system to the South’s fast-paced, capitalistic one. A few have even returned to the North, complaining that they had been treated like second-class citizens in the South.
Ms. Han got off welfare in nine months, suggesting that she was adapting quickly to her new life. But Kim Yong-hwa, the head of the NK Refugees Human Rights Association of Korea, who knew Ms. Han, said she had been carrying an emotional burden.
She had originally fled the North for China in the wake of the famine that killed millions of North Koreans in the late 1990s, according to Mr. Kim. He said she became one of the thousands of North Korean women sold by human traffickers to rural Chinese men looking for wives.
Such women live with the constant fear of being returned to North Korea and sent to a labor camp. Rights groups say that many of the women’s Chinese husbands exploit that vulnerability and sexually abuse them.
Some North Korean women in that situation have made their way to South Korea with children they had in China, only to face the stigma of being a single mother in the South, along with all the other difficulties of adjusting to life there.
Ms. Han initially came to the South alone, leaving a young son behind with her husband, according to Mr. Kim, who said he helped arrange her escape through Thailand, using smugglers. She paid the smugglers $2,000 after arriving in the South and getting cash support from the government, Mr. Kim said.
“But she terribly missed her son in China,” he said.
In 2012, Ms. Han asked her husband, an ethnic Korean, to join her in South Korea with their son. The man found work at a shipyard. Another son — Dong-jin — was born in 2013. They soon discovered that he had epilepsy.
South Korea’s shipbuilding industry entered a slump, and Ms. Han’s husband lost his job. In 2017, the family moved back to China.
Last September, Ms. Han returned to South Korea with Dong-jin, having divorced her husband, according to Mr. Kim. He said she called him, sounding depressed. She was afraid she wouldn’t be able to work, because she couldn’t find a child-care center that would accept an epileptic child. He said he advised her to apply for welfare benefits.
What happened to Ms. Han and Dong-jin after that is not clear.
North Korean defectors are closely supervised by the government for five years, but that time period had expired. The district office says Ms. Han never applied for welfare. Other North Koreans in Seoul have said that she did not have close friends among them.
She apparently could not afford a cellphone, meaning she would have been even more isolated. In her last months, her only income was $165 per month in government child support. In March, when Dong-jin turned 6, that amount was cut in half. A social worker visited in April and reported that no one was home.
On May 13, Ms. Han withdrew the last money in her bank account: $3.20.
On July 31, a meter man went to the apartment because the gas and water bills had gone unpaid for months. The smell was terrible, and he called the police. (Neighbors later told reporters that they thought it had been from a compost pile.)
The police later estimated that Ms. Han and Dong-jin had died in late May. Forensic investigators found no evidence of poisoning or physical trauma, nor was there any sign of a break-in. The refrigerator was empty except for a bit of chili powder.
Lee Jung-bin, an emeritus professor of forensic medicine at Gachon University near Seoul, said that starvation would be hard to prove in such a case, even if circumstantial evidence pointed to it. “If they don’t find any clear clues, like poisoning, forensic examiners will have to settle for ‘cause of death unknown,’ ” he said.
Many other questions are unanswered. Why didn’t Ms. Han ask for emergency assistance at the district office? Why didn’t she report her son’s illness, which would have entitled them to disability support? Kang Mi-jin, a North Korean defector-turned-journalist in Seoul who has been investigating the case, said Ms. Han could have withdrawn $4,500 that she had originally deposited to secure the apartment.
“She either didn’t know how to navigate the South Korean system and find the help that was available, or just felt so hopeless about her situation that she gave up trying,” Ms. Kang said.
Another North Korean refugee, Lee Min-bok, said: “She died not because she didn’t have any food, but because she had no hope.”
Helping defectors from the North has not been a political priority for South Korea in recent years, as the government has focused on improving ties with Pyongyang. And as the economy has slowed, there has been resistance to increasing subsidies for the refugees, who some see as competitors in a tough labor market.
But the deaths of Ms. Han and her son have unsettled many people. Government officials stood in silence in their memory this month, at a meeting to discuss how to repair gaps in the welfare system for defectors.
Later, they announced that the government would check in with all 31,000 North Koreans living in the South, to make sure that anyone who needed help received it.