An investigation published Friday by the Mexican newspaper Milenio documented that 591 migrants were sexually abused in the last six years in the United States by U.S. Immigration and Customs Enforcement (ICE) agents.

The probe, based on reports, statistics and internal audits of the U.S. Office of Justice Program and ICE, indicated that the abuses mainly were against women and took place in ICE detention centers, where migrants “should have been held” until their immigration status could be determined and their cases processed.