The heartbroken family of Harry Dunn has said the teenager was killed in a "big fireball" which was captured on CCTV from a nearby RAF base.
The 19-year-old died when his motorbike crashed into a car outside RAF Croughton in Northamptonshire on August 27.
Anne Sacoolas, 42, who allegedly collided with the teenager, fled home to the United States following the fatal incident. It is believed she was driving on the wrong side of the road.
Mrs Sacoolas is reportedly married to a US intelligence official and was granted diplomatic immunity after the crash, though that protection is now in dispute.
Mr Dunn's mother, Charlotte Charles, and the teenager's father, Tim Dunn, told a press conference in New York that they felt let down by the decision to allow Ms Sacoolas to flee the country.
The teenager's parents called on Ms Sacoolas to return to the UK to face justice, saying: "It's the right thing to do."
The family said CCTV evidence of the moments leading up to the crash made it "a clear-cut case".
When asked if the footage had been sourced from the RAF base, a Northamptonshire Police spokeswoman said: "Yes, I believe so."
Speaking at the press conference on Monday, a tearful Mrs Charles told reporters: "We just want to know that she is being brought back to the UK.
"You know, that would be a huge step in the right direction. It's the only right thing to do. It's the only humane thing to do."
She added: "All of our grief has gone on hold, it's coming out in other horrific ways, your legs feel like lead, you're in pain morning until night that no painkillers can take away.
"You're not able to cry, because we can't understand this whole situation as to why she (Anne Sacoolas) would have left us without wanting to meet us back then.
"She needs to get on the plane and get back to the UK, just do the right thing.
"It shouldn't be that difficult, it shouldn't have been this difficult, she surely didn't have to go."
Mrs Charles said the family has been told there is CCTV evidence showing Ms Sacoolas leaving the RAF base "on the wrong side of the road".
She added: "CCTV follows her all the way down the road on the wrong side of the road and you see Harry's headlight of his motorbike and then there is a big fireball when his bike went up.
"So it should have been a clear-cut case. It should have been simple and I promised Harry and we promised Harry as a family when we'd lost him that night, when we were talking to him in the hospital when we'd lost him already, that we would make sure justice was done."
The teenager's father also called on US President Donald Trump to act in an effort to secure justice for his son.
Mr Dunn said: "There's just no way I can start grieving yet, as a family we can't start, we need this resolved.
"Somewhere, somebody has made a decision to give this lady immunity.
"On that night there was an accident, a lady made a mistake, she killed our son, she didn't mean to kill him, she didn't mean to have an accident, but you cannot walk away from that and just leave and expect nothing to happen.
"Our boy died and he deserves to have some justice. That's all we want.
"I would say to him (President Trump) as a man, as a father, how could you let this happen? If you are a father and your child died, surely you'd want that person to own up and take responsibility for their action?"
Speaking after the press conference, Mr Dunn called on the suspect to "come out of hiding" and "set an example" to her own children.
Mr Dunn also said "something is not right" after the family were sent a letter from the Foreign and Commonwealth Office explaining that Ms Sacoolas does not have diplomatic immunity.
He said: "It just doesn't seem to sit right with me.
"It just seems like such a long-winded way around things and I think they just need to stop messing about."
The family reiterated their hope to secure Mrs Sacoolas a suspended sentence, rather than immediate custody, so as not to take her away from her family.
But they said their hopes of a meeting between the two parties should happen "in her own words, in a room, on our terms" back in the UK.
