The 19-year-old’s family are set for a two-day judicial review hearing at the High Court in November where they allege the foreign secretary “obstructed justice”.
Northamptonshire Police attempted to blame the media for "clumsy" remarks despite chief constable Nick Adderley being quoted in full.
A family spokesperson said footage of a near-miss close to RAF Croughton had "sent shivers down my spine and made me feel sick."
Two men in their twenties have also been arrested.
The 19-year-old was killed in a motorbike crash in Northamptonshire on August 27.
Anne Sacoolas, the wife of a US diplomat, is believed to have been driving on the wrong side of the road when she hit Dunn’s motorbike.
Anne Sacoolas has asked to be interviewed by officers from Northamptonshire Police.
A spokesperson for Dunn's parents said the decision was 'further compounding the family's misery'.
Suspect Anne Sacoolas said she had been 'devastated' by the 'tragic accident'.
Family of teenager killed in a crash are caught up in a row with the US over diplomatic immunity.
The victim, Harry Dunn's, parents have described being 'trapped in a living nightmare' since the teenager's death.
The victim's mother said the family had been left with 'nothing, no justice'.
A report said the safety of the children was "seriously undermined."
More than 2,000 homes temporarily lost power.
A woman was taken to hospital suffering from burns after the hot air balloon she was in crashed in Northamptonshire on Sunday
A policeman who came to the aid of an elderly man struggling with his shopping after he got on the wrong bus has been hailed
A hot air balloon had to make an emergency landing in a busy street causing mayhem - but the pilot said it was the safest
Britain's new police commissioners are under fire for handing top jobs to the "cronies" that helped them get elected. Rows
A Chinese businessman wanted on suspicion of murdering a family of four in their own home has been arrested in Morocco, police
Police in Morocco have arrested a man believed to be a Chinese businessman wanted on suspicion of murdering a family of four