BULGARIA - PENAL PROCEDURE CODE
Part two. EVIDENCING
Chapter thirty six. PROCEDURES IN CONNECTION WITH INTERNATIONAL COOPERATION ON PENAL CASES
Section III. International Legal Assistance in Penal Cases
Art. 473 (2) Turning over persons detained in custody, in order to be interrogated as witnesses or experts, shall only be allowed in exceptional cases at the discretion of the respective district court on the grounds of papers submitted by the other state or the international court of justice, provided that the person gives his/her consent for being turned over and provided that his/her stay in the other state will not extend the term of his/her detention in custody .
1. States Parties shall, in accordance with the provisions of this Part and under procedures of national law, comply with requests by the Court to provide the following assistance in relation to investigations or prosecutions:
(f) The temporary transfer of persons as provided in paragraph 7;
(a) The Court may request the temporary transfer of a person in custody for purposes of identification or for obtaining testimony or other assistance. The person may be transferred if the following conditions are fulfilled:
(i) The person freely gives his or her informed consent to the transfer; and
(ii) The requested State agrees to the transfer, subject to such conditions as that State and the Court may agree.
(b) The person being transferred shall remain in custody. When the purposes of the transfer have been fulfilled, the Court shall return the person without delay to the requested State.