British detectives will travel to the U.S. to interview the wife of an American diplomat who left England while a suspect in a vehicle collision that left a teenager dead, police said Tuesday.

Anne Sacoolas, 42, was allegedly behind the wheel of a vehicle that fatally struck Harry Dunn, 19, as he was riding his motorcycle near RAF Croughton, a military base in Northamptonshire, England on Aug. 27.

Despite leaving the country, "the suspect has cooperated fully with the police and with the authorities," said Nick Adderley, the chief constable for the Northamptonshire Police, during a news conference. Adderley said Sacoolas "requested to be interviewed by British police officers" in the U.S.

"Lawyers have clearly stated that the suspect wants to be personally interviewed by officers from Northamptonshire police in order for them to see her and the devastation that this has also caused her and her family," Adderley said.

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She did not want to submit a written statement, which she had the right to do, according to Adderley.

He said that Sacoolas spoke with police at the scene of the accident, and talked with them again the next day before invoking diplomatic immunity, which forced police to seek a waiver.

Adderley said that under law the police had to leave Sacoolas alone until a decision was made on the request to waive Sacoolas' diplomatic immunity. He said police were told on Sept. 16 that the waiver had been declined and Sacoolas had left the UK.

Adderley did not refer to Sacoolas by name because she had not yet been interviewed and the case file was incomplete. Once the file is submitted, prosecutors will determine whether they plan to press criminal charges against Sacoolas.

"You can't complete the file until you have an account from the suspect. And this is one of the reasons that we are not naming her," Adderley said. "We don't know the full circumstances behind what led to that collision."

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He said the detectives would travel to the U.S. as soon as they had their visas.

Dunn's parents, Charlotte Charles and Tim Dunn, as well as Prime Minister Boris Johnson, have called for Sacoolas to return to the U.K.

Last week, Dunn's parents met with President Donald Trump in Washington where he surprised them by offering an unexpected meeting with Sacoolas.

Charles said she and Dunn were "shocked" by Trump's offer and declined the meeting under such unusual circumstances. They said any such meeting should happen in England with therapists and mediators on hand.

Contributing: David Jackson