The parents of Harry Dunn have urged the woman accused of causing his death to apologise, saying it is "never too late to say sorry".
It is a year since Harry died while riding his motorbike near RAF Croughton in Northamptonshire, which is home to a US Air Force communications station.
The car that collided with him was allegedly driving on the wrong side of the road and it is believed the driver was Anne Sacoolas, the wife of a US diplomat.
She left the UK, claiming diplomatic immunity, and - despite being charged with causing death by dangerous driving - she has remained in the US since.
Harry's mother Charlotte Charles told Forces News that the family would "love" to hear from Mrs Sacoolas to say she was returning to the UK.
She said: "It's never too late to reach out, it's never too late to say sorry, it's never too late - as she did on the side of the road that night - admit that she'd made a mistake, it's never too late."
Mrs Charles and Harry's father Tim Dunn said they were trying to keep an open mind about what happened the night the 19-year-old died.
Mrs Charles said: "We don’t have enough reasons to hate the woman we've never met."
Mr Dunn added: "And we don't know the full story, so we keep an open mind. We're disappointed that a human being would feel leaving would be acceptable.
"We struggle to come to terms with how anybody would think after they've done that, the right answer would be 'oh yeah, let's get out of here'."
Since Harry's death, the family's campaign has focused on getting Mrs Sacoolas to return to the UK and for changes to the rules regarding overseas personnel on UK roads.
The legal loophole that allowed Mrs Sacoolas to claim diplomatic immunity has now been closed.
The couple said they have also met Transport Secretary Grant Shapps and had been told that he would like to meet them again.
Mrs Charles said: "We are very much hoping that a full road safety review will be carried out."
The couple have regularly been in the news, speaking about their campaign for justice and their son, but behind closed doors they have at times struggled to cope with their grief.
Mr Dunn said that being able to focus on the campaign was helpful.
He said: "I think it has helped me cope quite well because I think I'd have been a complete mess for the last 12 months, whereas with what's happened and the way things have transpired and we've moved along, it helps to keep you focused.
"What happened to Harry was not right, should not happen to anybody, and I think that's the force that has been behind our focus and our drive really.
"I think trying to get justice for Harry has been the main thing. We've always said that from the very first night - Charlotte made a promise and we knew that what happened to Harry was not right and people needed to answer to that."
Mrs Charles described the campaign as giving the family "somewhere to direct our frustrations".
"It has helped us manage our own expectations, I think, to a certain degree and I think it has been a real good thing to throw our energies into. It has helped us through," she said.
She added: "I think everyone thinks they would never be strong enough to do something like this, but you find it, you find that strength. The amount of love that you have for your children."
When asked what Harry would think of the campaign and the determination and hard work it has involved, Mrs Charles said: "He'd be immensely proud of Team Harry, immensely proud.
"But the thing is he wouldn't have expected anything less because if the shoe was on the other foot and it was one of us or, heaven forbid, his twin, he would have been doing the same."