MASANJIA, China » The cry for help, a neatly folded letter stuffed inside a package of Halloween decorations sold at Kmart, traveled 5,000 miles from China into the hands of a mother of two in Oregon.

Scrawling in wobbly English on a sheet of onionskin paper, the writer said he was imprisoned at a labor camp in this northeastern Chinese town, where, he said, inmates toiled seven days a week, their 15-hour days haunted by sadistic guards.

"Sir: If you occasionally buy this product, please kindly resend this letter to the World Human Right Organization," said the note, which was tucked between two ersatz tombstones and fell out when the woman, Julie Keith, opened the box in her living room last October. "Thousands people here who are under the persicution of the Chinese Communist Party Government will thank and remember you forever."

The letter drew international media coverage and widespread attention to China’s opaque system of "re-education through labor," a collection of penal colonies where petty criminals, religious offenders and critics of the government can be given four-year sentences by the police without trial.

But the letter writer remained a mystery, the subject of speculation over whether he or she was a real inmate or a creative activist simply trying to draw attention to the issue.

Last month, though, during an interview to discuss China’s labor camps, a 47-year-old former inmate at the Masanjia camp said he was the letter’s author. The man, a Beijing resident and adherent of Falun Gong, the outlawed spiritual practice, said it was one of 20 such letters he secretly wrote over the course of two years. He said he stashed them inside products whose English-language packaging, he said, made it likely they were destined for the West.

"For a long time I would fantasize about some of the letters being discovered overseas, but over time I just gave up hope and forgot about them," said the man, who asked that only his last name, Zhang, be published for fear of reprisal.

He knew well the practices of the camp in question, which were corroborated by other inmates, and he spoke as other inmates did of their work preparing mock tombstones, the purpose for which they were uncertain. His handwriting and modest knowledge of English matched those of the letter, although it was impossible to know for sure whether there were perhaps other letter writers, one of whose messages might have reached Oregon.

If Zhang’s account truly explains the letter’s origin, the feat represents one of the more successful campaigns by a follower of the Falun Gong movement, which is known for its high-profile attempts to embarrass the Chinese government after being labeled a cult and outlawed in 1999.

Emboldened by an unusually open public debate in China that has broken out here in recent months over the future of re-education through labor, scores of former inmates have come forward to tell their stories. In interviews with more than a dozen people who were imprisoned at Masanjia and other camps around the country, they described a catalog of horrific abuse, including frequent beatings, days of sleep deprivation and prisoners chained in painful positions for weeks on end.

Several former inmates recounted the death of a fellow inmate, either from suicide or an illness that went untreated by prison officials.

"Sometimes the guards would drag me around by my hair or apply electric batons to my skin for so long, the smell of burning flesh would fill the room," said Chen Shenchun, 55, who was given a two-year sentence for refusing to give up a petition campaign aimed at recovering unpaid wages from her accounting job at a state-owned factory.

According to former inmates, half of Masanjia’s population is made up of Falun Gong practitioners or members of underground churches, with the rest a smattering of prostitutes, drug addicts and petitioners whose efforts to seek redress for perceived injustices had become an embarrassment for their hometown officials.

All agreed that the worst abuse was directed at Falun Gong members who refused to renounce their faith. In addition to giving the electric shocks, they said, guards would tie their limbs to four beds and gradually kick the beds farther apart. Some inmates would be left that way for days, unfed and lying in their own excrement.

"I still can’t forget the pleas and howling," said Liu Hua, 51, a petitioner who was imprisoned at Masanjia on three separate occasions. "That place is a living hell."

Even if they found the work exhausting, many inmates described the time spent in Masanjia’s workshops as a respite from mistreatment or the hours of "re-education classes" that often entailed an endless recitation of camp rules or the singing of patriotic songs while standing in the broiling sun.

Much of the work involved producing clothing for the domestic market or uniforms for the People’s Armed Police. But inmates say they also assembled Christmas wreaths bound for South Korea, coat linings stuffed with duck feathers that were labeled "Made in Italy" and silk flowers that guards insisted would be sold in the United States.

"Whenever we were making goods for export, they would say, ‘You better take extra care with these,’" said Jia Yahui, 44, a former inmate who now lives in New York.

Corinna-Barbara Francis, a researcher at Amnesty International, said that given the abundant moneymaking opportunities, abolishing or significantly reforming the system would prove daunting. In addition to the profits earned from the inmate labor, prison employees often solicit bribes for early release, or for better treatment, from the families of those incarcerated.

During labor shortages, inmates say, Masanjia officials simply buy small-time offenders from other cities on a sliding scale that begins at 800 renminbi, or about $130, for six months of labor. They include people like Zhang Ling, a 25-year-old from the eastern coastal city of Dalian who said she was among a group of 50 young women rounded up by the police last May during a crackdown on illegal pyramid sales schemes and sold to Masanjia. While there, she sewed buttons on military uniforms but was released 10 months early after a brother paid for her release.

Masanjia officials did not respond to faxes and phone calls requesting an interview. Approached one recent afternoon, a half-dozen guards on a cigarette break outside the women’s work camp refused to answer questions. One guard, however, made a point of correcting the way a question was phrased.

"There are no inmates here," she said sternly. "They are all students."

Sears Holdings, the owner of Kmart, declined to make an executive available for an interview. But in a brief statement, a company spokesman, Howard Riefs, said an internal investigation prompted by the discovery of the letter uncovered no violations of company rules that bar the use of forced labor. He declined to provide the name of the Chinese factory that produced the item, a $29.99 set of Halloween decorations called "Totally Ghoul" that include plastic spiders, synthetic cobwebs and a "bloody cloth."

Although he was released from Masanjia in 2010, Zhang, the man who said he wrote the letter, has vivid memories of producing the plastic foam headstones, which were made to look old by painting them with a sponge.

"It was an especially difficult task," he said. "If the results were not to the liking of the guards, they would make us do them again."

He estimated that inmates produced at least 1,000 headstones during the year he worked on them.

Zhang’s letter-writing subterfuge was complicated and risky. Barred from having pens and paper, Zhang said, he stole a set from a desk one day while cleaning a prison office. He worked while his cellmates slept, he said, taking care not to wake those inmates – often drug addicts or convicted thieves – whose job it was to keep the others in line. He would roll up the letter and hide it inside the hollow steel bars of his bunk bed, he said.

There it would remain, sometimes for weeks, until a product designated for export was ready for packing.

"Too early and it could fall out; too late and there would be no way to get it inside the box," said Zhang, a technology professional who studied English in college.

His account of life in the camp matched those of other inmates who said they produced the same Halloween-themed items.

Last December, Keith, the woman who bought the product in 2011 but did not open it until the following year, sent the letter she found to the federal Immigration and Customs Enforcement agency, which said it would look into the matter. An agency spokesman, citing protocol, said that he could not confirm whether an investigation was under way but that such cases generally took a long time to pursue.

For Keith, a manager at Goodwill Industries, the experience has been sobering. She said she previously knew little about China, except that most of her household goods were made there.

"When that note popped out and my daughter picked it up, I was skeptical that it was real," she said. "But then I Googled Masanjia and realized, ‘Whoa, this is not a good place.’"

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