The emails provide deeper insight into the agency’s use of Locate X, a powerful surveillance capability that allows law enforcement officials to follow a phone, and person’s, precise movements over time at the click of a mouse. In 2023, a government oversight body found that the Secret Service, Customs and Border Protection, and Immigration and Customs Enforcement all used their access to such location data illegally. The Secret Service told 404 Media in an email last week it is no longer using the tool.

“If USSS [U.S. Secret Service] is using Locate X, that is most concerning to us,” one of the internal emails said. 404 Media obtained them and other documents through a Freedom of Information Act (FOIA) request with the Secret Service.