Video report by ITV News Correspondent Neil Connery
Foreign Secretary Dominic Raab has urged the suspect wanted in connection with the death of teenager Harry Dunn to "do the right thing" and return to the UK if she is charged by UK authorities.
Anne Sacoolas is thought to have been driving on the wrong side of the road when she knocked Harry off his motorbike near the RAF Croughton base.
Ms Sacoolas has since sought diplomatic immunity - due to her husband's role with the US government as an intelligence official - and has not returned to the UK.
After meeting with Harry's family, Mr Raab said: “Earlier today, I had a constructive meeting with Harry Dunn's family. I appreciate how painful this is for them, and welcomed the chance to address a number of their concerns.
“We are united in our determination to get justice for Harry. The Government will do everything it can. I also reaffirmed my commitment to conclude the review of the arrangements at RAF Croughton by the end of the year to ensure they cannot be used in this way again.
“I appeal to Anne Sacoolas herself to do the right thing. If there is a charging decision from the Crown Prosecution Service, I urge her to come back to the United Kingdom and cooperate with the criminal justice process.
“Finally, I want to pay tribute to the tenacity of Harry’s family and friends and their determination to get justice for Harry. We will support them in any way we can.”
Harry Dunn’s family earlier hailed a positive meeting foreign secretary Dominic Raab, with his father telling reporters he has “come out with hope”.
Radd Seiger, spokesman for the 19-year-old’s family, who met with the chief of Northamptonshire Police on Tuesday morning, said Mr Raab would like to see suspect Anne Sacoolas return to the UK.
The family came out of the meeting in a positive mood and father Tum Dunn said: “This meeting was a lot better, he was more engaging, I found he came across more honest.”
Their meeting came days after ITV News obtained footage of Ms Sacoolas driving in the US, which Mr Seiger says caused mum Charlotte Charles to "collapse into a heap".
Asked if Mr Raab had seen the video, Mr Seiger said he "shook his head" when he watched it.
Earlier, the chief constable of Northamptonshire Police said he is confident a charge will be made “any time soon” in Harry Dunn's case, who was killed in a crash on August 27.
Nick Adderley, who met Harry’s father and Mr Seiger on Tuesday morning, said he must remain impartial during the investigation but that could change if a charge is made.
Mr Adderley told reporters: “We are optimistic that a charge is going to be coming any time soon, once that charge is out there then [I will be leading] how we move forward in terms of extradition.
“If there isn’t an extradition application I will want to know why. I am confident that there will be and, again, once that charge is laid then my impartiality in terms of not interfering with that process means that has gone slightly.
“At the end of the day there is a resident within the county that I am responsible for who has died on the road and no-one has been held to account for it, that’s not acceptable.”
Meeting with Dominic Raab
Mr Seiger described their meeting with the foreign secretary as "constructive" and "far better" than their previous encounter.
He also told reporters that Andrea Leadsom, who is the MP for Northamptonshire South, and Mr Raab both want to see Ms Sacoolas return to the UK.
He said: “We discussed a range of issues, including some of the problems that have arisen since the last meeting, the misunderstandings that ensued from that.
“We talked about the diplomatic immunity position – but one of the things that came across loud and clear for us, which hadn't come across before, is that both Andrea Leadsom and the Foreign Secretary Dominic Raab would like this lady to come back too and that's not something that we had heard.
How did Dominic Raab react to the video of Anne Sacoolas?
“In our darker moments we do wonder whether there is collusion between the governments and trying to keep Anne Sacoolas back in the United States but I personally found the meeting quite reassuring.
He added they agreed to stay in touch and "improve communication" and that Mr Raab had assured them "he is doing absolutely everything he can to give this family the justice they need and deserve".
On the next step, Mr Seiger said: “He was quite honest about it, he said it's not up to him, it's up to the police and the CPS and still to this day we are scratching our heads as to why the CPs has not authorised the charge."
Meeting with Nick Adderley
Both Mr Sieger and Mr Adderley described their meeting as positive and said their shared focus is to bring justice to the Dunn family.
Mr Sieger told reporters Harry’s mum was devastated after seeing pictures gathered by ITV News of suspect Ms Sacoolas driving in the US.
He said: “Charlotte has not been able to meet today with the chief constable because she is just in bits and pieces and seeing that footage of Anne Sacoolas seemingly moving on with her life.
“The impression that we formed was almost without a care in the world - that may not be fair but that’s what it felt [like], she just collapsed in a heap and I’ve struggled to pick her up ever since.”
Footage of Anne Sacoolas in the US
Mr Adderley highlighted the relationship between himself and the family is good, despite an earlier “fallout” over a tweet he previously posted.
He said: “I do want to make the point that the fallout, or the perceived fallout, between me personally, the chief constable, and with Radd and the family has been a total misunderstanding.”
He said certain tweets and conversations have been “completely misconstrued”.
“We are now at a place where we understand each other,” he added.
While Ms Cross was not present on Tuesday morning, she has previously said of her son: "Everyone loved him, we're utterly broken inside and out, everything hurts day and night, it's an effort to do anything, I ache from it, every limb, every internal organ hurts."
The 19-year-old's parents have said before they will do everything they can, even travelling to the US, to get "justice" for their "big-hearted" and "fun-loving" son.