Anne Sacoolas is suspected of being involved in the death of 19-year-old Harry Dunn, who was hit riding his motorbike.

Britain’s Prime Minister Boris Johnson urged the United States to reconsider granting immunity to a diplomat’s wife suspected of killing a teenager in a British road crash.

Johnson said he was prepared to intervene with President Donald Trump to secure the woman’s return to Britain to face investigation over the death of 19-year-old Harry Dunn.

“I do not think that it can be right to use the process of diplomatic immunity for this type of purpose,” the prime minister told reporters on a visit to a hospital.

“I hope that Anne Sacoolas will come back and will engage properly with the processes of law as they are carried out in this country.”

Dunn was killed on August 27 when his motorbike collided with a car near a Royal Air Force base in Northamptonshire in central England, which is used by the US military as a communications hub.

He was hit by a Volvo SUV travelling in the opposite direction, police said, adding only that they were treating an unnamed 42-year-old US woman as a suspect.

The US Embassy in London last weekend confirmed the vehicle had been driven by the wife of one of its diplomats, who had now left the country.

On the question of lifting diplomatic immunity, the mission said it was “rarely waived”.

The embassy was in “close contact” with UK officials. But it said it “will not comment on the identity of the driver”.

Media identified her husband as Jonathan Sacoolas, who worked at RAF Croughton, near the town of Brackley, which is home to the 422nd Air Base Group.

‘Immunity is rarely waived’

In a statement, Northamptonshire Police said the driver had initially “engaged fully” with their investigation and said she had no plans to leave Britain, but had now left.

“If we can’t resolve it then of course I will be raising it myself personally with the White House,” Johnson said.

Foreign Secretary Dominic Raab has raised the case with US ambassador Woody Johnson and also brought it up in a call Monday with US Secretary of State Mike Pompeo.

Raab “reiterated his disappointment with the US decision and urged them to reconsider,” a Foreign Office spokesman said.

Northamptonshire police said they were working through “diplomatic channels” to try to contact their suspect, who was never arrested.

The victim’s mother, Charlotte Charles, said she needed to know who killed their son to start the grieving process.

“We just don’t understand how you can just get on a plane and leave behind the devastation she has without even speaking to us or facing us, or an apology of any kind,” she said.

Charles added: “She’s got to be suffering as well – she’s a mum.

“Without knowing who this person is properly, we can’t begin to try and start our grieving process.”

In a statement received by AFP on Sunday, the US Embassy in London offered condolences to the victim’s family.

“Any questions regarding a waiver of the immunity with regard to our diplomats and their family members overseas in a case like this receive intense attention at senior levels,” it said.

“(They) are considered carefully given the global impact such decisions carry; immunity is rarely waived.”