The Biden administration has begun tracking all illegal immigrants released at the southern border into the United States, seeking to reverse course after losing track of nearly 50,000 migrants let go from Border Patrol custody under chaotic circumstances.

Starting in the fall, the Department of Homeland Security opted to conditionally allow noncitizens to leave through a process called parole, three people familiar with the federal immigration operation told the Washington Examiner. Under parole, migrants are still being discharged from Border Patrol facilities on the border, but their records have been digitally transferred to U.S. Immigration and Customs Enforcement, the federal agency responsible for tracking noncitizens within the country. Those released have also been outfitted with ankle monitors or have installed a phone app that allows authorities to keep tabs on them.