SEOUL, South Korea (CNN) - A North Korean defector has issued an emotional plea to one of the world's most powerful men, China's President Xi Jinping.
"My son is now four, please think of my son as you think of your grandson and take pity on him."
The defector has not seen his 4-year-old son since he was was detained by Chinese authorities, along with his mother -- Lee's wife, on November 4, while attempting to flee from North Korea.
"My son is only four so he probably doesn't understand what a jail is. Why is he in a cold room, what guilt does he carry to have been put in a cold jail cell? I'm angry at the world," said Lee.
To protect the family, CNN is using a pseudonym, Mr. Lee, and is blurring the faces of the family in photographs.
Lee, who now resides in South Korea, defected alone in 2015. He feared the long and difficult journey -- typically covering hundreds of miles across tough terrain -- was too dangerous for his wife and child, a decision he now bitterly regrets.
"While I was coming alone, I was thinking, even if I die, I must die alone, if I am captured I will surely die ... I carried poison with me in case I was captured ... I regret it to my bones that I came out alone."
In October of this year, Lee organized for his wife and child to be helped out of North Korea, but half way through the journey Chinese authorities arrested them along with eight other defectors in Shenyang, a city in northeast China. The pair had successfully crossed the North Korean border, and were preparing to travel through China to cross into South Korea where they would join Lee.
"I called them and they said they were captured, they were in handcuffs. I heard their urgent voices and then the line went dead." He has heard nothing since and is now unsure of their exact whereabouts.
China does not consider those escaping North Korea to be refugees, labeling them instead as "illegal economic migrants." Under such a policy they are routinely sent back to North Korea where they are met with almost certain punishment.
China's foreign ministry said last week it was unaware of the 10 defectors arrested, "China consistently upholds the handling of such matters in accordance with domestic and international law and humanitarian principles."
The number of defectors reaching South Korea is falling -- from 2,700 in 2011, the year former leader Kim Jong Il died, to around half that number last year, according to South Korea's Unification Ministry.
Increased border controls by both North Korea and China are thought to be the primary reason for the drop.
Reverend Kim Seung-eun and his Caleb Mission has helped defectors escape North Korea for two decades, personally claiming to have helped around 500 people.
Kim, who is now advising Lee, attributes their capture to wider changes. He says it now costs $20,000 to bring someone from North Korea to South Korea via China. Twenty, years ago it cost a fraction of that. He says that's a reflection of how much more difficult defecting has become.
"China who talks about human rights, have erected fences along the Tumen and Yalu rivers to arrest defectors," the pastor said.
Lee says those who plan to go to South Korea rather than settle in China are punished more harshly by North Korea.
"We call those people "express." My wife is "express," if she were sent back to North Korea, her punishment will be worse, being sent to the political camps would be the minimum."
Lee knows the North Korean prison system, spending five years in jail from the age of 16 with his father.
He says his crime was very small but his grandfather was originally from South Korea. For that reason he says his family was persecuted for decades. "Starvation is natural, human rights abuses ... many are beaten to death by the guards. Someone would steal food because they were hungry and they would be beaten to death ... of 3,000 inmates on average, about three a day would die."
Lee says his father died while he was in prison. He breaks down at the thought that his young son could be punished in the same way.
South Korea's Presidential office says they have asked China to handle North Korea defectors from a humanitarian perspective, a message given just before President Moon Jae-in met President Xi last Saturday in Vietnam, where a regional economic was held.
It gives Lee some hope as does a speech to South Korea's parliament by U.S. President Donald Trump last week where he listed North Korea's human rights abuses saying the country "is a hell no person deserves."
Lee is asking President Trump to intervene, "I've never seen someone give such a speech. Although we as North Koreans have experienced the living hell first hand, I don't think we could put it into words like that."