BULGARIA - PENAL PROCEDURE CODE
Part two. EVIDENCING
Chapter thirty six. PROCEDURES IN CONNECTION WITH INTERNATIONAL COOPERATION ON PENAL CASES
Section 1 Transfer of Convicted Persons
Art. 456. (1) When there are data that the person convicted by a Bulgarian court is in the territory of the state whose citizen he/she is, the chief prosecutor may address a request to the foreign authorities for detaining the person for whom a request will be done for accepting the execution of the sentence, while informing that there is an effective sentence with regard of this person.
(2) In the event of a submitted request for detaining a Bulgarian citizen by another state, Art. 64 and Art. 68 shall be applied respectively.
Request for arrest and surrender
EDIT.