After the American college student Otto Warmbier was released from a North Korea prison in 2017, unresponsive and not expected to survive, his father, Fred, spoke of a comforting phone call from President Trump: “It was gracious, it was nice and it felt good.”

During Mr. Trump’s State of the Union address in 2018, Fred Warmbier and his wife, Cindy, stood and wept while Mr. Trump spoke of the “menace” of North Korea and gave tribute to their son, who died days after his release.

On Friday, the Warmbiers emerged into the public eye again, this time with a blistering statement directed at the president. They said they could no longer be silent after the summit meeting this week with Kim Jong-un, the North Korean leader, and after hearing Mr. Trump say that he believed Mr. Kim’s claim that he did not know what had happened to Mr. Warmbier while he was in custody.

“We have been respectful during this summit process,” the Warmbiers said in a statement. “Now we must speak out. Kim and his evil regime are responsible for the death of our son Otto. Kim and his evil regime are responsible for unimaginable cruelty and inhumanity. No excuses or lavish praise can change that.”