The Contracting Party in whose territory a sentence of deprivation of liberty or a detention order has been imposed in a judgment which has obtained the force of res judicata in respect of a national of another Contracting Party who, by escaping to his own country, has avoided the execution of that sentence or detention order, may request the latter Contracting Party, if the escaped person is in its territory, to take over the execution of the sentence or of the detention order. The requested Contracting Party may, at the request of the requesting contracting Party, prior to the arrival of the documents supporting the request that the execution of the sentence or of the detention order or part of the sentence be taken over, and prior to the decision on that request, take the convicted person into police custody or take other measures to ensure that he remains in the territory of the requested Contracting Party.