Lawyers acting on behalf of Harry Dunn’s family have formally requested a record of all phone calls and text messages sent between his alleged killer and her husband about the fatal road crash.

The 19-year-old’s parents were given permission to begin the “discovery” process in their US civil claim against Anne Sacoolas on Tuesday – allowing them to ask for an array of documents ahead of a face-to-face legal battle with the suspect.

As part of their disclosure requests, the Dunn family’s lawyers have asked for all documents related to the teenager’s death, images taken at the scene of the collision and Sacoolas’s employment details.

Mr Dunn’s mother Charlotte Charles and father Tim Dunn’s legal team have also demanded all communications sent or received by the suspect from the moment she left RAF Croughton, to her arrival at her temporary Northamptonshire home.

The teenage motorcyclist was killed when a car crashed into his motorbike outside the US military base in August 2019.

Sacoolas, 43, had diplomatic immunity asserted on her behalf by the US Government and was able to return to her home country 19 days after the collision.

She was charged with causing death by dangerous driving but the US State Department refused to extradite her – describing the decision as “final”.

Mr Dunn’s parents were told on Tuesday they can expect a face-to-face legal showdown with Sacoolas before July 23 during the “deposition” phase of the civil claim – which will take place out of court.

A trial is due to be scheduled for the end of the year.

The Dunn family’s civil claim has unearthed a great deal of previously unheard material, such as the State Department roles held by both Mr and Mrs Sacoolas.

The Alexandria District Court in the US state of Virginia heard the couple’s work in intelligence was a “factor” in their departure from the UK – with the Sacoolases leaving for “security reasons”.

Judge Thomas Ellis gave the civil claim the go-ahead earlier this month.

Explaining the steps taken by the Dunn family’s lawyers, spokesman Radd Seiger told the PA news agency: “This is a legal step taken by the lawyers in the US as they pursue the parents’ objectives of getting justice for Harry and answers as to what happened on the night he died.

“After 18 months of feeling like they are coming up against a brick wall they are now feeling like they are making progress, which is always important in a campaign for justice.

“The steps the lawyers have taken, we believe, will shine a light on what happened, which is terribly important for their mental health even after all this time.”