The American woman who claimed diplomatic immunity after her alleged involvement in the death of Harry Dunn has asked to be interviewed in the US under caution by Northamptonshire police officers, according to the force’s chief constable.

Officers will travel to the US at the earliest opportunity to interview Anne Sacoolas, who was allegedly driving a car on the wrong side of the road when it crashed into the 19-year-old motorcyclist outside RAF Croughton, in Northamptonshire, on 27 August.

Nick Adderley, the Northamptonshire chief constable, said on Tuesday morning that he wanted to “provide clarity and put rumours to bed”.

He said: “I have offered to go and see the family on two occasions now and on both occasions that has not been able to happen. The reason for that not taking place is because the information being asked for by the spokesman – who is not their lawyer, by the way – I legally cannot provide.”

Adderley had been scheduled to meet Dunn’s parents, Charlotte Charles and Tim Dunn, on Wednesday afternoon but the family cancelled the meeting after it became clear he would not answer a series of key questions, according to Radd Seiger, spokesman for Dunn’s family. Adderley insisted this information was classified.

Although the police chief recognised the desire for answers, he called on Seiger to “exercise constraint” since his commentary was “unhelpful”.

However, Adderley said that the Dunn family discovered Sacoolas had returned to the US before they were informed by police. He confirmed Northamptonshire police were asked by the Foreign and Commonwealth Office not to inform the family for several days, so they could work out the next legal steps.

The suspect, whose husband was reportedly stationed at the airbase as an intelligence officer, has remained in contact with officers despite her return to the US.

“The suspect has cooperated fully with the police and with the authorities,” Adderley said. “She has also requested to be interviewed by British police officers under caution in the United States.”

In an “unprecedented” press conference, Adderley debunked reports that Sacoolas had left the UK without giving an account to police. He said she cooperated with police at the scene on 27 August and was breathalysed.

He said: “The very next day, police officers attended the home address of the suspect, where once again she cooperated with the police and gave an account regarding the circumstances of that collision.

“It was at that point diplomatic immunity was mentioned and on that very day, Northamptonshire applied for the waiver against that.”

She returned to the US on an air force plane shortly afterwards, and Adderley said there was nothing more police could do after diplomatic immunity had been flagged.

He added: “On Monday 16 September, Northamptonshire police are informed by the Foreign and Commonwealth Office that the waiver had been declined and the suspect had left the UK.”

It came after further criticism from Seiger on Tuesday. He said the family appeared to be receiving “contradictory” statements from the authorities which was compounding their misery.

After the press conference, he said: “The family have lost all faith and confidence in both the police and the Foreign Office. There is a clear breach of the victim code here – first and foremost they did not tell the family for a number of weeks that she had gone.”

Dunn’s parents will meet the shadow foreign secretary, Emily Thornberry, on Tuesday and she is expected to call for a parliamentary inquiry into the teenager’s death.

On Monday, Dominic Raab, the foreign secretary, told the Commons he had commissioned a review into immunity arrangements for US personnel and their families at RAF Croughton in light of the case.

Raab said there were “no barriers to justice being done” for Dunn.

He also said the UK government believed diplomatic immunity “clearly ended” for Sacoolas, 42, when she left the country for the US.