Charlotte Charles and Tim Dunn face lawyers acting on behalf of Anne Sacoolas in the US.
The parents of Harry Dunn said they had “spoken for him” after giving evidence in a damages claim against their son’s alleged killer in the US.
The 19-year-old died near RAF Croughton in Northamptonshire in August 2019, when a car driven by suspect Anne Sacoolas hit his motorbike.
She later left the country, claiming diplomatic immunity.
His mother, Charlotte Charles, said: “We stood up and spoke for him as he cannot speak for himself now.”
Mrs Sacoolas’s car struck Harry Dunn’s motorbike moments after she left the RAF base where her husband worked for a US intelligence agency.
The 43-year-old was charged with causing the teenager’s death by dangerous driving after her departure from the UK, but an extradition request was rejected by the US State Department in January last year.
Mrs Charles and Tim Dunn faced lawyers acting on behalf of Mrs Sacoolas and gave legal testimony under oath during their depositions after flying out to Washington DC.
Mrs Sacoolas must also give legal testimony by the end of August as part of the civil claim brought against her and her husband Jonathan.
The depositions are part of a process in the Dunn family’s claim, in which relevant documentation will be handed over ahead of a trial at the end of the year.
Alexandria District Court in the US state of Virginia heard the couple’s intelligence work was a “factor” in their departure from the UK – with the Sacoolases leaving for “security reasons”.
Harry Dunn’s mother said: “We can’t go into the detail of what happened at all but we were required to come out to the USA to do the depositions in person and that is just what we have done.
“Although it has been an arduous day and a difficult trip, right smack in the middle of the pandemic, the reality is that it is easy for us to come to the States and for us to talk about our son Harry and the impact his loss has had on all of us.
“We are enduring life, not living it, but we will do everything in our power to get justice for our boy and for ourselves.
“He deserves that. We deserve that, and we will not stop until we have achieved justice in both the civil and criminal cases.”
Mr Dunn’s father said Harry was “going to leave a huge legacy behind him with everything our campaign has achieved”.
“This trip could not have gone any better and I feel we have taken another giant step towards getting justice in the civil claim,” he said.
“We know the path is now clear in the criminal case too and I want to appeal on behalf of my family to the authorities in both London and Washington to do everything within their power to help alleviate our suffering a little and speed up the process of justice in the criminal case.”
Earlier this month, Foreign Secretary Dominic Raab said the path was now clear for the UK to push for a form of “virtual trial or process”.
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