On March 14, the woman suspect Ri, and another suspect surnamed Ji, pretended to be the victim's nephew and a distant family member and asked the mine boss for 1.2 million yuan in compensation, the police said.

After many discussions, the boss finally decided to pay them 520,000 yuan in compensation.

But Dongxiang police remained suspicious and sent officers to the victim's birthplace to check his identity, which they determined was fake.

On April 18, police detained the nine suspects.

"We are still working with police to further investigate the case," a prosecutor surnamed Liu from Dongxiang prosecutors' office told China Daily on Tuesday.

An earlier report by Xinhua News Agency quoted Wang Xinguo, deputy head of the Dongxiang county police bureau, as saying that there were a number of similar cases across the country.

"We will conduct an intensive inspection in the surrounding mining industries to see if there are similar cases, and if the suspects may be related," Wang said.

Wu Yongming, vice-president of the provincial association of social sciences, said that enterprises should also be blamed for hiring mentally-disabled workers, which is banned.

"If enterprises follow the standard employment procedure, the gang won't have a chance to get a mentally-disabled man employed in the first place," he said.