The Mondulkiri Provincial Court on Monday charged two men with poaching endangered black-shanked douc langur monkeys in the Keo Seima Wildlife Sanctuary, an official said.

Touch Rath, 51, and Chhin Sreng, 40, were caught by sanctuary rangers on Saturday with guns and two of the dead monkeys. They were later charged with poaching, court spokesman Meas Bros said.

Bros said both lived in Keo Seima district and were charged under Article 61 of the protected areas law and face one to five years jail, as well as fines of 15 million to 150 million riel, (about $3,673 to $36,735).

Wildlife Conservation Society (WCS) technical adviser Tan Setha said that the monkeys were likely poached for their stomachs due to the belief that the organs possess medicinal qualities. “It is not rare to see douc [langur] stomachs for sale in some places,” Setha said.

According to the WCS, between June 2016 and the end of last month, there were 159 recorded cases related to the poaching and wildlife trade in Keo Seima Wildlife Sanctuary, with the majority involving the confiscation of equipment and 17 cases involving wildlife.

The area is home to about 20,000 langur monkeys – the largest such population in the world – as well as over 60 other species listed as threatened by the International Union for the Conservation of Nature.