Fugitive diamond merchant Nirav Modi lodged at Wandsworth Prison in South West London since May 2018 for extradition to India, has been contesting his return to India for four years now. What he has been incarcerated for, is technically called “provisional arrest” — a temporary measure enacted to prevent an absconding accused from hoodwinking the law and remaining untraceable.
A provisional arrest is an unusual measure and is resorted to by the country of residence or transit of an accused. It usually is only an interim measure to ‘immobilise a fugitive’ for a relatively short duration—60-90 days in most cases, to allow time for the country where the accused is wanted, to prepare and send a ‘formal’ extradition request.
However, it isn’t unusual for a fugitive to be released on bail even during the period of provisional arrest if the detaining country and its criminal justice system is convinced that the accused is not a flight risk.

