The families could reel off all the times they had called the media and written to Washington, but after all that trying, they had never heard anyone who mattered say anything like it: Most Mexican immigrants, Donald J. Trump declared in his first campaign speech, were “rapists” who were “bringing drugs, bringing crime” across the border.

Now he had come to meet them, the families of people killed by undocumented immigrants, and they wanted to tell him he was right.

One son had been struck by a truck, another shot just around the corner from home. Different causes of death, but the driver, the gunman, all the perpetrators were the same, the parents said: people who never should have been in the country in the first place.

Sitting alone with them at the Beverly Wilshire Hotel in July 2015, the candidate distributed hugs as the families wept. When the campaign had called, most of them had been told only that they were going to meet with Mr. Trump. But then the group was ushered into the next room, where the campaign had invited reporters to a news conference.