They walked out of court in downtown Buffalo a little before 5 p.m., worn down from a hearing that had dragged late into the afternoon.

The man and woman climbed into their black S.U.V. With nightfall approaching and powerful wind gusts rolling in from Lake Erie, they began following the Google Maps instructions to get them home to Syracuse, N.Y.

They took an exit ramp and veered right, not focusing on where they were going. They didn’t notice the blue sign overhead, warning that they were “entering a federal inspection area.”

Within seconds, Victor and his sister Johanna realized their mistake. Victor — a Colombian asylum seeker who had spent the day in immigration court fighting to stay in the United States — was driving across the Peace Bridge toward the Canadian border. There was no way to turn back.

On the other side of the Niagara River, a patrol car pulled up alongside their S.U.V. as they approached the security plaza. Victor noticed the word “Canada” painted on its side.

It was Thursday, Feb. 6, barely two weeks into the second Trump administration, which by then was already deep into its promised immigration crackdown.