In February 2018 Jessie Kim found out that she had been sending money to a dead man.
Ms Kim, now a 27-year-old student in Seoul, fled North Korea for China in 2011.
She had been sending her father in Yanggang province in the North around $1,000 a year since she arrived in South Korea in early 2014.
Two years later she doubled the contributions, working several part-time jobs,
after her aunt told her that her father had been in an accident and needed money for medical bills.
But another call from her aunt last winter, claiming that her father was asking for yet more money, made her suspicious.
"He wasn't the kind of man to ask his daughter for money," she says.
Ms Kim made enquiries through the broker who had facilitated the transactions.
She eventually found out that her father had died in the accident in 2016 and that the money had gone to her aunt's family instead.
Ms Kim's case illustrates the pitfalls of supporting relatives in a country that is all but cut off from global communications and financial-services networks.
Ordinary North Koreans are not allowed to receive money or even phone calls from abroad.
Foreign banks are hesitant to handle any transaction associated with the North, for fear of falling foul of sanctions,
intended to curtail its nuclear programme, that have been imposed by America and others.
Yet the relationship between the 30,000-odd North Korean refugees in South Korea
and their relatives back home shows that the North is much less closed than at first appears.
A growing proportion of those who have settled in the South manage to send money home.
In 2018, 62% of refugees surveyed by the Database Center for North Korean Human Rights (NKDB), an NGO in Seoul,
said they had transferred funds to relatives or friends in North Korea, up from 50% in 2013.
Most respondents say they sent between $500 and $2,000 a year, which was mostly spent on basic living expenses, health and education.
The annual total may run into the tens of millions of dollars.