LONDON — An American woman suspected of killing a teenage motorcyclist in central England in August by driving on the wrong side of the road has been charged with causing death by dangerous driving, British prosecutors said on Friday.

The woman, Anne Sacoolas, the wife of an American diplomat, left for the United States under diplomatic immunity soon after the crash, and the British foreign secretary, Dominic Raab, has urged her to return to Britain.

The British Crown Prosecution Service said on Friday that it had started proceedings, but that it was up to the Home Office to decide whether to formally seek Ms. Sacoolas’s extradition through diplomatic channels.

“Following the death of Harry Dunn in Northamptonshire, the Crown Prosecution Service has today authorized Northamptonshire Police to charge Anne Sacoolas with causing death by dangerous driving,” Janine Smith, chief crown prosecutor, said in a statement.