U.S. Immigration and Customs Enforcement has stopped publicly revealing where it is holding thousands of detainees who are subject to final deportation orders, an unannounced move that has made it far more difficult for lawyers and relatives to find them, according to current and former officials familiar with the practice.

ICE removed those detainees from its online detainee locator system on Sept. 15, according to three current and former ICE officials who spoke on condition of anonymity because they were not authorized to discuss the change. Several lawyers contacted by The Associated Press confirmed their clients vanished from the system this week, and the American Immigration Lawyers Association warned its members about the situation Friday.

The move represents a stark departure from previous practice and highlights the hardline nature of President Donald Trump’s immigration crackdown, leaving thousands of detainees exceedingly hard to trace and potentially unable to exercise all of their legal options.

The practice, which applies to detainees who have received final orders of removal from an immigration court, could speed deportations by making last-minute legal challenges harder to pursue, immigration lawyers said. Nearly 16,000 people who were arrested and booked into ICE detention in July were subject to final removal orders, more than a third of the overall bookings, according to ICE data obtained by the Deportation Data Project based at U.C. Berkeley and UCLA.

The practice does not apply to detainees held at a detention facility in Adelanto, California or at temporary holding facilities in Minneapolis, New York City or suburban Chicago, the sources said. Judges have ordered ICE to list detainees in those facilities in the online locator promptly upon their arrival, as part of litigation over their detention practices.