The letter about horrendous working conditions at a Chinese labour camp was found by Julie Keith, a mother of two in Portland, Oregon, stuffed between the Styrofoam headstones of the Totally Ghoul decoration box sold at Kmart.
There was some doubt as to the letter’s authenticity when it was uncovered in October, but now a former inmate at the Masanjia camp in Shenyang, has come forward as the author.
Mr Zhang, a 47-year-old from Beijing who can only be identified by his surname for safety, said he secretly wrote 20 letters over two years at the camp.
Barred from having pens and paper, Mr Zhang said he stole a set from a desk while cleaning a prison office one day.
He stashed his notes inside products with English packaging, hoping they would make it to someone who could come to the workers’ rescue.
A Kmart spokesman, said in a statement that an internal investigation uncovered no violations of company rules that bar the use of forced labour.