Harry Dunn’s parents have dropped their legal claim against Northamptonshire police after concluding the force was “absolved of any blame” over their son’s death. The 19-year-old’s family are set for a two-day judicial review at the high court in November where they allege the foreign secretary “obstructed justice” by allowing the suspect in the case, Anne Sacoolas, to leave the UK. Northamptonshire police were brought into the legal claim in January as Dunn’s mother, Charlotte Charles, and father, Tim Dunn, sought to understand how Sacoolas, the wife of a CIA agent working at the US intelligence base RAF Croughton in Northamptonshire, was able to claim diplomatic immunity following the fatal crash in August last year. It is understood the force will now only be involved in the claim as an “interested party” on the request of its chief constable, Nick Adderley. It is also understood the force will not seek costs against the family for its involvement in the proceedings. The Dunn family decided to discontinue proceedings against the police after alleging that documents disclosed for court proceedings demonstrated the force was “kept in the dark” by the Foreign Office (FCO). Recent documents, seen by PA Media, showed Northamptonshire police said it was not informed by the FCO of the arrangements that allowed Sacoolas to claim diplomatic immunity. The force also claims the FCO did not tell it about the risk of Sacoolas being withdrawn from the UK or the existence of a waiver in respect of her husband Jonathan’s immunity – preventing officers from interviewing him as a witness. In December last year, Sacoolas was charged with causing Dunn’s death by dangerous driving but an extradition request submitted by the Home Office was rejected by the US secretary of state, Mike Pompeo, in January. The US state department described the decision as final but the UK and US have since agreed to amend the “anomaly” that allowed Sacoolas to claim diplomatic immunity. The Dunn family’s spokesman, Radd Seiger, said of the dropped claim against the police: “Having carefully reviewed the documents disclosed by the foreign secretary, the parents are now satisfied that the police are absolved of any blame and could have done no more to ensure that Mrs Sacoolas was brought to justice. “Our case remains that the documents clearly show how the police investigation was effectively stopped in its tracks abruptly when the Foreign Office told the police shortly after Harry died that Mrs Sacoolas had diplomatic immunity. “We say the documents reveal that the Foreign Office kept the police in the dark for 14 days about the uncertainty surrounding Mrs Sacoolas’ claim to immunity. They failed to tell them that Mrs Sacoolas was planning to leave the country, and then did not tell the police that she had gone until the day after she left. “In the United Kingdom, it is the police’s responsibility to establish who has diplomatic immunity, not the Foreign Office, yet he [UK foreign secretary, Dominic Raab] and his team did just that – the parents say unlawfully.” A Northamptonshire police spokesman said: “This is an ongoing legal matter and it would therefore be inappropriate to comment further at this time.” The FCO has been approached for comment.