The House Committee on Natural Resources sent the World Wide Fund’s US branch a demand letter on Monday requesting internal documents for an ongoing investigation that seeks to determine if the US government funded anti-poaching organizations that committed human rights violations.

A BuzzFeed investigation revealed that the World Wide Fund for Nature (WWF), the world’s largest conservation organization, had funded and equipped ranger and paramilitary forces that engaged in abusive practices including torture, sexual assault, and extrajudicial killings in national parks in Asia and Africa.

These discoveries prompted a bipartisan investigation into whether US taxpayer dollars supported forces responsible for the abuses. While the WWF provided information in a preliminary meeting in April, the congressional committee letter explained that “[q]uestions remain regarding the extent to which WWF was aware that entities it funded and equipped may have committed a wide range of human rights abuses” and asked for a wide range of documents, including human rights reports and staff training manuals, to assess how much the US branch of the organization funded and knew of these abusive operations.

The letter stated that “[d]espite the importance of protecting wildlife and endangered species from extinction, the United States must not be party to violations of basic human rights.”  WWF has until July 19 to respond to the demand.