The family of , who was killed in a collision outside a military base in Northamptonshire, have said they plan to take legal action against the Foreign Office and are seeking an investigation into the police.
A spokesperson for the family said it is their intention to refer Northamptonshire Police to the Independent Office for Police Conduct for its action during the crash investigation.
Lawyers have begun the process of drafting letters; one called a “letter of claim”, which is a prelude to a judicial review, about the advice given to Northamptonshire Police by the Foreign Office, and the other to request an investigation by the IOPC into the conduct of the force.
The family spokesperson, Mr Seiger, said this was "just the beginning" and would also, at a later stage, review the role of the US administration in the granting of diplomatic immunity to the American suspect, Anne Sacoolas.
The family’s lawyers, led by Geoffrey Robertson QC, will also consider the prospect of civil action against 42-year-old Mrs Sacoolas, but that is yet to be decided.
The US diplomat’s wife is believed to have been driving on the wrong side of the road when she hit Mr Dunn’s motorbike outside RAF Croughton in Northamptonshire on August 27.
Mr Seiger said he was relieved to finally get the ball rolling, after initially telling PA the family was considering a judicial review while campaigning for justice in the US.
Speaking on Thursday, he said: “We are reviewing the Foreign Office’s decision to advise Northamptonshire Police that Mrs Sacoolas had the benefit of diplomatic immunity – because when that is declared the police can do nothing.
“They have been lying. They have been lying and withholding information from us.
“We felt sick to the stomach when we went through the timeline of events last night.
“We feel really, really badly let down. This is just wrong and it should never have happened.
“We are absolutely clear that the Foreign Office’s decision to advise Northamptonshire Police that Mrs Sacoolas had the benefit of diplomatic immunity was unlawful and we will be seeking to launch a judicial review of that decision and have it quashed.”
Speaking of Northamptonshire Police’s role in investigating the incident, Mr Seiger said the family had “deep concerns” over the way the case had been handled.
He said: “It is completely inappropriate for Northamptonshire Police to go to the expense of travelling to the US to interview her under caution.
“It was at her request, to show the world how ‘devastated’ she is. If that is the reason they are going that is not the correct use of taxpayers’ money. She could do that over Skype or on the phone.
“We don’t know why they are out there or what they are up to. Despite numerous requests they have refused to update us.”
Asked about what the family’s lawyers had said to him in the meeting, Mr Seiger said: “They said to me ‘you are absolutely right – and it is wrong of Nick Adderley to tell me to tone down my public commentary.’
“He said it was ‘amongst the best investigations’ he had seen. He has not followed the Victims’ Code so how can he say that?”
Speaking on whether the Northamptonshire force had followed the Victims’ Code, Victim Commissioner Dame Vera Baird QC said: “I cannot by law comment on the handling of individual cases but there is a principle here.
“The Victims’ Code makes clear the entitlement to be informed by the police of the following information and to have the reasons explained within five working days of a suspect being: arrested, interviewed under caution, released without charge, released on police bail, or if police bail conditions are changed or cancelled.
“In the most serious crimes such as this the rule is that this must happen within one working day.
“The family solicitor clearly challenges the police on whether they have complied with this part of the Victims’ Code. These code rights need to be statutory with robust mechanisms to properly challenge non-compliance with consequences when the Code is broken.
“This tragic case highlights the urgent need for a systemic change to the status of victims’ rights. The government’s proposed Victims’ Law needs to deliver these requirements.”
A Northamptonshire Police spokeswoman said: “Northamptonshire Police are happy to support the IOPC with any concerns raised by the family of Harry Dunn.”
A Foreign Office spokesperson said: “We have done everything we can properly to clear a path so that justice can be done for Harry’s family.
"As the Foreign Secretary set out in Parliament, the individual involved had diplomatic immunity whilst in the country under the Vienna Convention on Diplomatic Relations. We will respond to any legal action in due course.”