9. Subject to the provisions of its domestic law and its extradition treaties, the requested State Party may, upon being satisfied that the circumstances so warrant and are urgent and at the request of the requesting State Party, take a person whose extradition is sought and who is present in its territory into custody or take other appropriate measures to ensure his or her presence at extradition proceedings. 10. A State Party in whose territory an alleged offender is found, if it does not extradite such person in respect of an offence to which this article applies solely on the ground that he or she is one of its nationals, shall, at the request of the State Party seeking extradition, be obliged to submit the case without undue delay to its competent authorities for the purpose of prosecution. Those authorities shall take their decision and conduct their proceedings in the same manner as in the case of any other offence of a grave nature under the domestic law of that State Party. The States Parties concerned shall cooperate with each other, in particular on procedural and evidentiary aspects, to ensure the efficiency of such prosecution. 11. Whenever a State Party is permitted under its domestic law to extradite or otherwise surrender one of its nationals only upon the condition that the person will be returned to that State Party to serve the sentence imposed as a result of the trial or proceedings for which the extradition or surrender of the person was sought and that State Party and the State Party seeking the extradition of the person agree with this option and other terms that they may deem appropriate, such conditional extradition or surrender shall be sufficient to discharge the obligation set forth in paragraph 10 of this article. 12. If extradition, sought for purposes of enforcing a sentence, is refused because the person sought is a national of the requested State Party, the requested Party shall, if its domestic law so permits and in conformity with the requirements of such law, upon application of the requesting Party, consider the enforcement of the sentence that has been imposed under the domestic law of the requesting Party or the remainder thereof. 13. Any person regarding whom proceedings are being carried out in connection with any of the offences to which this article applies shall be guaranteed fair treatment at all stages of the proceedings, including enjoyment of all the rights and guarantees provided by the domestic law of the State Party in the territory of which that person is present. 14. Nothing in this Convention shall be interpreted as imposing an obligation to extradite if the requested State Party has substantial grounds for believing that the request has been made for the purpose of prosecuting or 18