The lawyer for the family of a teenage motorcyclist killed in a crash has appealed for “witnesses” to the suspect’s return to the United States.
Anne Sacoolas, the wife of a US diplomat, left the UK despite being a suspect in the fatal crash with Harry Dunn, 19, on 27 August.
The US government has not waived Mrs Sacoolas’ diplomatic immunity.
Lawyer Radd Seiger asked for those with information “before, during, or after her departure” to come forward.
Mr Dunn’s parents, who have previously said they are considering civil action against Mrs Sacoolas, are set to fly out to the US on Sunday and will visit both New York and Washington DC.
Mr Seiger said they would be “engaging with the media and politicians as they reach out for support from all Americans and to ask them to put pressure on the US administration to do the right thing”.
On Wednesday, US President Donald Trump said his administration would speak to Mrs Sacoolas “very shortly and see if we can do something where they meet”.
But a briefing note held by Mr Trump at the press conference appeared to suggest Mrs Sacoolas would not be returning to the UK after being granted diplomatic immunity.
Mr Dunn’s mother Charlotte Charles said the US’s apparent approach was “beyond any realm of human thinking”.
His father Tim Dunn said: “We have to go to America and speak to the American people. We can’t let this be swept under the carpet.”
The family met with Foreign Secretary Dominic Raab on Wednesday, which they have since described as a “publicity stunt”.
Afterwards Mr Raab said the justice process was “not being allowed to properly run its course”.
Chief Constable of Northamptonshire Police Nick Adderley said the investigation into the crash was “carrying on” and that a file would be passed to the Crown Prosecution Service soon.
Mr Dunn died after his Kawasaki motorcycle was involved in a crash at about 20:30 BST near the RAF base at Croughton in Northamptonshire, where Mrs Sacoolas’s husband Jonathan had been working.
Police have said CCTV of the crash in which the teenager died shows a Volvo travelling on the wrong side of the road.