Nearly half of the people living in the U.S. illegally are believed to have entered the country legally and stayed on expired visas. To combat the problem, the federal government on Thursday is launching one of its most ambitious efforts to track them.
U.S. Customs and Border Protection will begin capturing facial and eye scans of foreigners entering the country at San Diego's Otay Mesa port of entry on foot. By February, foreigners going to Mexico on foot through the checkpoint will get scanned.
