Two South African brothers have been charged with fueling a black-trade rhinoceros horn market by selling illegal hunting trips to Americans at gun shows and expositions across the U.S. The men were indicted in Alabama, where one of them maintained a residence and bank accounts, after selling illegal rhino hunts from 2005 to 2010.

Dawie and Janneman Groenewald, who operated their guide business through Out of Africa Adventurous Safaris, told American customers they were shooting “problem” rhinos and offered discounted rates—the caveat being that hunters were not permitted to export their trophies home.

The brothers then profited off the sale of rhinoceros horns in the lucrative black market. According to a story in the Montgomery Advertiser, horns can sell for up to $35,000 per pound. Many people believe that rhino horns have medicinal benefits.

Eleven American hunters have been identified as customers, but have not been charged with breaking the law. However, U.S. Fish and Wildlife Service director Dan Ashe said, “These hunters should have known better.” At a press conference about the indictment on Thursday, Ashe also said the U.S. plans to extradite the two brothers, who are currently in South Africa.

Photo from Out of Africa Adventurous Safaris