A mentally ill man who beat a 13-year-old to death has reportedly spent the last decade in a cage, with a pan for a toilet and chains around his feet.

Wu Yuanhong, 42, gets three meals a day delivered by his 74-year-old mother Wang Muxiang at their home in Ruichang, Jiangxi Province, in the country's east, according to the Information Daily newspaper.

Pictures show him wearing only a T-shirt and his underwear.

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He was reportedly diagnosed with schizophrenia at the age of 15 and in 2001 he was jailed for beating a 13-year-old boy to death. Judicial authorities released him a year later as his illness meant he was not legally responsible for his actions.

He was placed in shackles after his release, but his mother built the cage after he escaped and walked around his home village scaring local residents, the report said.

The family built a stronger structure to hold him after he got out again.

His mother told the paper: "My son may be insane, and beat someone to death, but he's still my son.

"To use my own hands to place him in a cage was very hard to take, like being stabbed with a knife.

"Every time I delivered food, I would sit at his cage and cry. Now my tears are dried up."

She said while she tried to find someone who would weld her a strong cage for her son, local blacksmiths refused out of fear the sick man might attack them in revenge if he ever escaped, so she built it herself.

"I welded the cage while crying heavily," she said. "Although he suffers from mental illness and killed a person, he still is my son. Thinking I am making a cage to lock him in, my heart was broken."

Many mentally ill people in China go without proper treatment due to a lack of resources and qualified professionals, particularly in the countryside.

The Ministry of Health said in 2010 that there were only about 20,000 psychiatrists to serve the country's population of 1.35 billion, the state-run China Daily reported.

The Information Daily quoted local officials as saying they had supported the family with donations of oil and rice, adding Jiangxi had launched limited subsidies for poor families with mentally ill relatives.