She and her husband Jonathan Sacoolas, a US intelligence officer, were spirited out of Britain on a private flight from a US air base after the incident.
The 42 year old mother-of-three, claimed diplomatic immunity to avoid prosecution despite not being on the official London diplomatic list.
The Foreign Office confirmed however that Mrs Sacoolas and her husband, 43, were given diplomatic immunity prior to their arrival in the UK under the Vienna Convention.
The immunity is extended to intelligence officers and other Americans working on military bases including RAF Croughton in Northamptonshire where the crash happened.
Mr Seiger said the family did not accept that Mrs Sacoolas had diplomatic immunity and would be meeting with the chief constable of Northamptonshire police next week.
The family has called on the force to charge Mrs Sacoolas and initiate extradition proceedings.
Mr Seiger said he the family had told the FCO and US officials that they were prepared to “have a conversation” if there were security concerns related to Mr Sacoolas’ work, but had been rebuffed.
“If there is some good reason why this lady should have been recalled, the family would have been open to that discussion. But they just completely ignored us,” he said.