Parents of Harry Dunn, the 19-year-old British man killed in a car crash involving an American woman, are speaking out for the first time in the U.S. about the tragic loss of their son. Tim Dunn told "CBS This Morning" he was able to speak to his son at the crash scene before he was taken to the hospital.

"I could see broken bones out of his arms and stuff. But he was talking," Tim said, choking up with emotion. He added, "I called out to him and said, 'Harry, it's your dad. They're going to fix you. They're going to fix you. Be calm. Let them help you.' He stopped moaning because he was complaining that he couldn't breathe very well."

Tim said his son had to be sedated, so he told Dunn, "'Harry, they're going to sedate you now. This is for your best. You're going to be OK. We'll see you later at the hospital,' something I said like that. And then they sedated him and then that was the last time."

Police say American Anne Sacoolas fatally struck Dunn in August after she was driving on the wrong side of the road. The car was leaving a U.S. military base when it hit his motorcycle. Sacoolas, who is reportedly married to a U.S. intelligence officer, was granted diplomatic immunity after the crash and flew back to the United States. That immunity has been called into question.

Britain's foreign secretary sent a letter to Dunn's parents saying the U.K. government's position is that immunity is no longer relevant, reports CBS News correspondent Imtiaz Tyab. CBS News reached out to the State Department to confirm if that means Sacoolas no longer has immunity – or can be extradited – and are still waiting on an answer.

In a statement from her lawyers, Sacoolas said she wants to meet with Dunn's family. She said she is "devastated" and that the reporting has, in her words, "been inaccurate in many respects."

Dunn's mother, Charlotte Charles, said of Sacoolas' statement, "Why has it taken so long? You know, it's seven weeks tomorrow since we lost our boy. And we feel that that statement should have come out from her right from the beginning instead of getting on a plane and running home."

Charles said they had been advised not to meet with Sacoolas during their trip to the U.S., but her message was clear: "Just do the right thing."

"We are still very open to meeting her, but it needs to be in a controlled environment in the U.K.," Charles said, adding, "It's just she needs to get on the plane. She needs to go back to the U.K. It's to just do the right thing. It shouldn't be that difficult. It shouldn't have been this difficult."

Charles said she wants people to know Dunn was an "amazing lad."

"He was a big lad with a big heart. And lots and lots of people loved him. He loved them equally back. If anyone was in trouble, he had their back. If anyone he felt was in the wrong he would stand up and speak openly and try and get things sorted out and make them do the right thing. And that's the legacy that he's left us to do. We're honoring him by trying to do this," Charles said.