An Interpol notice has been circulated worldwide making Anne Sacoolas in effect a fugitive from justice if she sets foot outside her native United States...

Radd Seiger, a lawyer for the Dunn family, said Northamptonshire police had confirmed that the Interpol notice had been issued, adding that this meant in the Foreign Office’s view she did not have diplomatic immunity at the time of her initial arrest. “Red notices would not be served on valid diplomats,” he said. “It means she would be arrested if she sought to leave the United States.” He continued: “It is time for her to come back to the UK and on behalf of the family I urge the authorities both in London and Washington to make that happen. It is time to do the right thing.” He said she would receive a fair trial in the UK...

A red notice has been described as an international wanted person’s notice but is not in itself an arrest warrant.. . It cannot compel the law enforcement authorities in any country to arrest someone who is the subject of a red notice. Each member country decides what legal value it gives to a red notice and the authority of their law enforcement officers to make arrests.

https://www.theguardian.com/uk-news/2020/may/11/interpol-red-notice-issued-for-arrest-of-anne-sacoolas

... The US State Department continues to insist that at the time of the accident, and for the duration of her time in the UK, Ms Sacoolas had immunity from criminal jurisdiction.

https://www.independent.co.uk/news/uk/crime/anne-sacoolas-wanted-interpol-red-notice-harry-dunn-death-a9508886.html