BULGARIA - PENAL PROCEDURE CODE
Part two. EVIDENCING
Chapter fourteen. METHODS OF EVIDENCING
Section II. Interrogation
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(3) The interrogation of the accused shall start by a question of he/she does understand the accusation and shall be invited, if he/she wishes, to state in a free-text all what he/she knows under the case.
Fair trial standards
Rights during trial - unsworn oral or written statement in defence
EDIT.