The family at the centre of a row over diplomatic immunity after their son died in a crash have launched an appeal for witnesses to the suspect leaving for the US.

Harry Dunn died when his motorbike crashed into a car outside an RAF base on August 27.

The suspect, 42-year-old Anne Sacoolas – who is reportedly married to a US intelligence official, was granted diplomatic immunity following the crash.

The 19-year-old victim’s parents, Charlotte Charles and Tim Dunn, have now decided to take their fight to the US, and have said they will visit both New York and Washington DC to gain support from Americans and “put pressure on the US administration to do the right thing”.

Harry Dunn death
The family of Harry Dunn, mother Charlotte Charles (left) and father Tim Dunn (right) with their partners (PA)

Before travelling to New York City, the spokesman and adviser to Harry’s family, Radd Seiger, said they would like to launch a direct appeal to anyone who saw Mrs Sacoolas leave the UK.

He said: “Anne Sacoolas left England to return to the USA following the road traffic collision outside RAF Croughton on August 27.

“The United States government has claimed she has the benefit of diplomatic immunity and has refused to grant the waiver sought by the British government.

Harry Dunn death
Spokesman Radd Seiger for the family of Harry Dunn, flanked by mother Charlotte Charles and father Tim Dunn (PA)

“I would urge anyone, on either side of the Atlantic, who has any information relating to Mrs Sacoolas’s return to the United States, whether before, during, or after her departure, to please come forward.”

On Friday, the Prime Minister said America is “absolutely ruthless” in its safeguarding of Mrs Sacoolas following the decision to grant her diplomatic immunity.

Boris Johnson said although President Trump was sympathetic towards Harry’s family’s views on the use of diplomatic immunity, the US are “very reluctant” to allow citizens to be tried abroad.

Speaking of taking their campaign to the US, Harry’s family said in a statement that they “continue to live in a nightmare” and have so far been unable to grieve after his death.

A statement released on behalf of the family said: “As if losing Harry was not enough, they now find themselves having to expend enormous time and energy, which they can ill afford, generating sufficient publicity to garner public support to persuade the US government to help achieve closure and return the driver Mrs Sacoolas to England to face the consequences of her actions.

“Sadly, all such efforts to date have failed. The parents, after a brief period of rest, are therefore now taking their campaign to the USA and will visit New York City and Washington DC over the coming days, 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.

“They are looking forward to making as many new friends in the USA as possible.

“Harry’s family will simply not leave matters where they are and will do whatever it takes, including taking legal action if necessary, to secure Justice 4 Harry.”