The parents of a teenage motorcyclist who died in a road accident have appealed to US President Donald Trump to intervene, after the wife of an American diplomat suspected in the case left the country.

In an emotional plea, Charlotte Charles and Tim Dunn asked Trump to help bring justice for the death of their 19-year-old son, Harry Dunn, calling on authorities to waive her diplomatic immunity.

“Just to look and listen to what has happened and to try to see it from our point of view and our heartache, and hopefully he can help with bringing her back to the UK, so we can get on and do our stuff, and do the justice and help us to start grieving again,” Dunn told CNN’s New Day when asked what his message was for Trump.

The accident has become an international dispute, drawing in UK Prime Minister Boris Johnson, who has promised to talk to the US ambassador as well as Trump if necessary. Johnson named the suspect as 42-year-old Anne Sacoolas on Monday.

Police say the suspect was driving on the wrong side of the road when she and Harry Dunn collided. Sacoolas was originally cooperating in the case, police have said, but that she left the country despite assuring them she would remain in the UK.

CNN’s attempts to contact Sacoolas have beem unsuccessful.

‘We’re completely broken’

Harry Dunn’s mother broke down in tears as she said she hoped the suspect knew of her family’s suffering.

“You know we’re six weeks on, and even though this supposed diplomatic immunity has put a cloak around her, protected her, surely as a human and a mum herself, I just want her to know that we’re completely broken. She’s broken our family. We’ve all got to try and find another way of living our lives. We don’t know where to start,” Charlotte Charles said.

Dunn died in the accident on August 27 in Northamptonshire in central England, which is home to a Royal Air Force station controlled by the US Air Force.

Under the 1961 Vienna Convention, diplomats and their family members are typically immune from prosecution in their host country.

The US State Department told CNN Saturday that diplomatic immunity is “rarely waived.”

“Any questions regarding a waiver of immunity with regard to our diplomats and their family members overseas in a case like this receive intense attention at senior levels and are considered carefully given the global impact such decisions carry,” it added.

The US Embassy in London refused to comment on the identity of the suspect for privacy and security reasons.