LONDON — British police officers investigating a crash that killed a teenage motorcyclist in Britain in August will travel to the United States to interview the American suspect who claimed diplomatic immunity and fled the country shortly after the accident, the police said on Tuesday.

The development is the latest in a weekslong episode that has engaged Britain and the United States in a diplomatic push-and-pull as the teenager’s family traveled between the two countries in a search for answers and justice.

The suspect in the case, Anne Sacoolas, 42, is the wife of an American diplomat who worked at a Royal Air Force base that hosts a United States Air Force communication station. As such, she was entitled to immunity under a 1995 treaty between Britain and the United States, Britain’s foreign secretary, Dominic Raab, told Parliament on Monday.

She is suspected of being the driver of a car that the police say was traveling on the wrong side of the road when it collided with a motorcycle ridden by Harry Dunn, 19, on Aug. 27 in Brackley, a town about 60 miles northwest of London.