British Prime Minister Boris Johnson directly contacted President Trump Friday about a fatal car crash after the U.S. State Department refused to extradite the American suspect involved, his office said.

"The Prime Minister raised the tragic case of Harry Dunn, and the need to secure justice for Harry's family," a Downing Street spokesperson said, according to Sky News. "He reiterated the need for the individual involved to return to the UK."

Dunn, 19, was killed in August of last year during a head-on collision that 42-year-old Anne Sacoolas is charged with causing through dangerous driving. Sacoolas claimed diplomatic immunity and returned to the U.S., but a Dunn family spokesperson suggested that UK authorities considered trying her in absence.

"I am informed by officials in London that the UK authorities are urgently considering all their options following the rejection of the extradition request including trying #annesacoolas in her absence and issuing an Interpol Red Notice," spokesperson Radd Seiger tweeted on Saturday.

STATE DEPARTMENT REFUSES TO EXTRADITE AMERICAN CHARGED IN DEADLY UK CRASH

Dunn's mother, Charlotte Charles, indicated she would never stop fighting for Sacoolas' extradition. "It doesn't matter when, whether it's this administration or the next. The extradition request is always going to be over Anna Sacoolas's head, and we're never going to give up," she said recently.

ANNE SACOOLAS, WIFE OF US DIPLOMAT, FORMALLY CHARGED IN DEATH OF BRITISH TEENAGER

The State Department says Sacoolas had diplomatic immunity when she was in Britain, and to send her to face criminal charges would set “an extraordinarily troubling precedent.”

British Foreign Secretary Dominic Raab called the U.S. decision “a denial of justice.”

“I called the U.S. ambassador earlier to express the government’s disappointment about this decision,” Raab said, adding that U.K. officials are “urgently considering our options.”

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Under the Vienna Convention on Diplomatic Relations, families of diplomats are granted immunity from arrest or detention. British prosecutors, however, maintain that immunity does not apply to dependants of consular officials based outside London.

Dunn’s family has urged Sacoolas to return and face British justice, and met with U.S. President Donald Trump in Washington as part of their campaign.

The Associated Press contributed to this report.