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The wife of a U.S. diplomat claimed "immunity" and fled the United Kingdom after becoming a suspect in an August hit-and-run that killed 19-year-old Harry Dunn.

According to Sky News, Northamptonshire police said "their initial findings show that Harry was riding his motorbike on the correct side of the road, but that a woman, who pulled out of the airbase onto the wrong side of the carriageway, hit him head-on. He suffered multiple injuries and died later in hospital."

Northamptonshire Police Superintendent Sarah Johnson said in a statement that "Harry Dunn's family deserves justice and in order to achieve this, a full and thorough investigation, with the assistance of all parties involved, needs to take place."

The U.S. Embassy in London said it is in contact with British law enforcement and confirmed the suspect left the U.K., but it declined to reveal the person's identity, citing "security and privacy considerations."

Reuters reported Friday that Northamptonshire police "applied for a waiver from diplomatic immunity to allow investigations and an interview" but the U.S. declined the waiver.

"I have called the U.S. Ambassador to express the U.K.'s disappointment with their decision, and to urge the Embassy to re-consider it," said U.K. Foreign Secretary Dominic Raab.

Speaking to Sky News, Harry Dunn's father Tim said the family is "disgusted, appalled, how she could be having this cloak wrapped around her. I'm angry that someone could do this and then get on a plane and go."

Charlotte Charles, Harry's mother, said "we don't know how we can start to grieve for him."

"We have nothing. No justice," said Charles. "We have nothing to put our minds at rest that she's even remorseful."