Chinese parents whose young adult or teenage children have gone missing from the central province of Henan in recent years say they have been forced to form an unofficial support network to search for them, in the face of official indifference.
One father surnamed Miao from Henan's capital Zhengzhou said his son, among several thousands in the province who have disappeared in recent years, went missing a decade ago.
He has been trying to find him ever since, and suspects he has been kidnapped into a slave labor factory.
Miao said his entire life now revolves around the hunt for his missing son, whose photograph he always keeps with him.
"This is [a photo] of my son," Miao, a retired People's Liberation Army (PLA) soldier, told a recent documentary aired by RFA's Mandarin Service.
"He will be 32 years old this year. He went missing in 2004, when he was 25."
In Henan alone, more than 5,000 families say their teenage or young adult children, most of them boys or young men, have gone missing in recent years.
The number who have been officially rescued from such bondage numbers only in the hundreds, across the whole of China.
Miao said he began combing hotels, bathhouses, and other public places in the city for his son soon after he went missing.
"I thought maybe he was working in those places," Miao said. "But it was no use."
Since then, Miao has banded together with more than 100 families in a similar situation.
Many of them now believe their children were kidnapped into the illegal brick kilns that circle Zhengzhou, where they are being held against their will and forced to perform slave labor.
Such "black factories" aren't uncommon in China, and first made global headlines in 2007 with the liberation of thousands of enslaved workers, some of them children, from a brick kiln in the northern province of Shanxi.
But parents say the local authorities appear unwilling to crack down on the practice, and that police are often slow to take missing persons reports seriously.
Zhengzhou mother Li Yuqiang, whose son went missing at the age of 15, said police had largely ignored her reports about her son.
"The police told me that boys of 15 and 16 are just beginning to get online," Li said. "They said I shouldn't be afraid and that he probably went to an Internet cafe."
"They said it didn't amount to a [missing persons] case."
Another member of the group, who gave only her surname Diao, said she had spotted her son on a television report about "black factories."
"He was just in the shot for the briefest time, then he disappeared again," Diao said.
But when she went looking for the factory, which she tracked down to a village called Kaolao, near Henan's Yongji city, the owners had fled, taking the workforce with them.
"There was ... no sign of human life," Diao said. "But the bunk beds were all still there."
"When I saw it, it was exactly the same as it had been on the television."
She said she had learned from an escaped fellow worker who knew her son that he had felt unable to risk escaping because of injuries to his legs.
Torture and abuse
Tales of torture and physical abuse are rife among escapees of such factories, although they are generally only shared among other concerned parents, and rarely get an airing in China's state-controlled media.
Official Chinese figures show that 10,000 children are kidnapped annually across the whole country, while the U.S. State Department says that figure is likely closer to 20,000, according to U.S. film-maker and blogger Charlie Custer, who has followed the issue closely in recent years.
But such figures, even if accurate, are unlikely to include the large numbers of young adults who are lured into slavery with the promise of paid work by recruiters skilled at playing on the hopes and fears of young people struggling to get a head start in a difficult economy.
Reported by RFA's Mandarin Service. Translated and written in English by Luisetta Mudie.