A 28-year-old migrant worker from Chongqing municipality who told police he mysteriously lost his left kidney in South China’s Guangdong province has admitted that he sold his kidney, according to the Chongqing Economic Times on Wednesday.

“I sold my left kidney of my own will for 20,000 yuan ($3,200), ” Shu Zhen told his father who went to visit him in the hospital on Tuesday, the newspaper reported.

Shu went to Machong People’s Hospital in Dongguan on Feb 23 for a stomachache. He claimed that he woke up in a local hotel with 20,000 yuan in his pockets, but couldn’t remember anything from the previous four days, the report said.

A doctor found his left kidney missing and called the police, although Shu tried to stop him.

Police are holding Shu for further investigation, although he has refused to say why he sold his kidney, the newspaper said.

According to police, the kidney removal operation was done very professionally. Most of those involved in the case have been captured, police said.