The “ghost wedding” is an ancient ritual involving the family members of a deceased person who posthumously marry them to another dead person in order to placate their restless souls, giving them less reason to haunt the living. It is a ritual that is still practiced by some Chinese today.

Unfortunately, the ritual has taken a more sinister turn as there simply aren’t enough dead brides, and some people are willing to resort to murder to meet the increasing demand.

Three men in China’s northwestern province of Gansu have been charged with murdering two mentally disabled women and selling their bodies as ghost brides in neighboring Shaanxi province.

On April 13, police in Wuxi, Shanxi discovered the corpse of a woman in a car driven by three men named Ma, Teng, and An.

Ma and An confessed that they had abducted the victim by posing as matchmakers before murdering her with a sedative injection. She was sold as a ghost bride for 35,000 yuan ($5,259). They also admitted to killing another woman the same way in February.

Ghost weddings have been banned in China since 1949, but rising fortunes throughout the country have contributed to their comeback. Last year, 15 female corpses were looted from tombs in Shanxi and sold as ghost brides.

Although a ghost wedding can be as simple and symbolic as relocating the remains of a dead woman to lie next to those of her newly-wedded dead husband, things get much more difficult when there are no deceased women to be found.

A man in Liangcheng County, in Inner Mongolia, admitted to police last year that he murdered a woman so that he could sell her body as a ghost bride. In 2013, four men were sentenced to two years in prison for digging up 10 female corpses that they sold for a total of $39,000.

In Shanxi, where the latest murders occurred, high numbers of male fatalities occur from the region’s many mining accidents. Given that China’s gender imbalance greatly favors males over females, there simply aren’t enough women to go around.

Even for the living, being single is a taboo that requires the intervention of family members. Although some demographics have welcomed single-hood as a kind of freedom, like “leftover women”, many Chinese regard being single as an act of non-filial piety.