The Department of Homeland Security’s independent Office of Inspector General has taken up the formal investigation into the leak of confidential government information in late June that forced Immigration and Customs Enforcement to call off a nationwide operation, according to the federal agency.

“Last month, U.S. Immigration and Customs Enforcement (ICE) became aware of an apparent leak related to a planned enforcement operation. Leaks of law enforcement sensitive information jeopardize the safety of ICE officers and agents who have sworn an oath to uphold the law. ICE referred the incident to its Office of Professional Responsibility, which, in accordance with its normal procedures, referred it to the DHS Office of Inspector General,” ICE said in a statement issued Monday morning.