LONDON (AP) — The family of a British teenager killed when his motorcycle collided with a car allegedly driven by an American diplomat’s wife plan to take legal action against the U.K. foreign policy chief for his actions in the aftermath of the accident.

The family of Harry Dunn say they will bring a bring a private prosecution against Foreign Secretary Dominic Raab, accusing him of misconduct in a public office and perverting the course of justice.

Northamptonshire Police interviewed Anne Sacoolas about the crash that killed 19-year-old Dunn in August near RAF Croughton, a British base used by the U.S. military in southern England. Shortly after that, she left Britain.

Sacoolas claimed diplomatic immunity. U.S. officials have refused to extradite her.

In October, Raab told lawmakers that the Foreign Office had consistently called for Sacoolas’s immunity to be waived and that the police could not have lawfully prevented her departure.

The teenager’s parents allege Raab allowed Sacoolas to leave the country without involving the police, at a point when her claim of diplomatic immunity was “ambiguous.’’

Charlotte Charles and Tim Dunn have also accused Raab of preventing the police from conducting their investigations into their son’s death.