Over the past year inside the public corridors of 26 Federal Plaza, masked federal agents have detained people as they arrive for immigration hearings. The detainments happened as families are funneled through a gauntlet of officers, a badge and paperwork in a clenched hand, children watching as arrests unfold, and relatives embracing when it’s over. The practice plays out in front of attorneys, the press and other court-goers, yet leaves the arresting officers largely anonymous behind face coverings.