Harry Dunn, 19, died in hospital after his motorbike crashed with a Volvo
The wife of an American diplomat has left the UK after being made a suspect in an investigation into a fatal crash.
Harry Dunn, 19, of Charlton, Banbury, was killed when his motorbike crashed with a car near RAF Croughton in Northamptonshire on 27 August.
Police said they wanted to interview an American woman in her 40s.
Foreign Secretary Dominic Raab said he had called the US Ambassador to express his “disappointment” she had left the country.
Supt Sarah Johnson said: “Northamptonshire Police followed all of its usual procedures following the incident, including liaising closely with the suspect, who engaged fully with us at the time and had previously confirmed to us that she had no plans to leave the country in the near future.
“The force is now exploring all opportunities through diplomatic channels to ensure that the investigation continues to progress.
“Harry Dunn’s family deserve justice and in order to achieve this, a full and thorough investigation, with the assistance of all parties involved, needs to take place.”
The crash happened on the B4031 near RAF Croughton, Northamptonshire
RAF Croughton is a United States Air Force communications station.
Harry’s mother Charlotte Charles told Sky News: “Everyone loved him, we’re utterly broken inside and out, everything hurts day and night, it’s an effort to do anything, I ache from it, every limb, every internal organ hurts.
“We don’t know how we can start to grieve for him.”
Mr Raab said: “I have called the US Ambassador to express the UK’s disappointment with their decision, and to urge the Embassy to re-consider it.”
The US Embassy in London said: “Embassy officials are in close contact with the appropriate British officials on this matter.
“Due to security and privacy considerations, we cannot confirm the identity of the individuals involved, but we can confirm the family has left the UK.”