The parents of Otto Warmbier, whose son died in 2017 after he was returned from a North Korean prison, slammed Kim Jong Un and his “evil regime” after President Donald Trump said the North Korean dictator claimed he was unaware of Otto’s treatment while imprisoned.

“We have been respectful during this summit process. Now we must speak out,” said Fred and Cindy Warmbier in a statement Friday. “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.”

The statement comes after President Trump said Thursday he takes Kim Jong Un “at his word” that the dictator was unaware of the alleged mistreatment of the American college student who died after being imprisoned there.

Kim “tells me he didn’t know about it, and I will take him at his word,” the president told reporters during a press conference Hanoi, Vietnam.

“It just wasn’t to his advantage to allow that to happen. Prisons are rough, they’re rough places, and bad things happened,” the president added.

President Trump said Kim “felt very badly about it”, before adding that “He knew the case very well, but he knew it later. In those prisons, those camps, you have a lot of people.”

Warmbier, a University of Virginia student had been visiting North Korea with a tour group when he was detained. A court there sentenced him to 15 years of hard labor for the alleged offense.

Pyongyang officials returned Otto to the U.S. in a coma in June 2017, and he passed away days later in Cincinnati, Ohio.

Last year, a U.S. judge ordered North Korea to pay more than $500 million in a wrongful death suit filed by Warmbier’s parents.

U.S. District Judge Beryl Howell in Washington harshly condemned North Korea for “barbaric mistreatment” of Warmbier, awarding punitive damages and payments covering medical expenses, economic loss and pain, and suffering to parents Fred and Cindy Warmbier.

The Associated Press contributed to this report.